com.vaadin.flow.server.frontend.

java.lang.Object
- com.vaadin.flow.server.frontend.FrontendUtils

```
public class FrontendUtils
extends Object
```
A class for static methods and definitions that might be used in different locations.

Since:

2.0

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

static class FrontendUtils.UnknownVersionException
Thrown when detecting the version of a tool fails.

Field Summary

Fields
Modifier and Type	Field and Description
`static String`	`BRIGHT_BLUE`
`static String`	`CHUNKS` A key in a Json object for chunks list.
`static String`	`CSS_IMPORTS` A key in a Json object for css imports data.
`static String`	`DEAULT_FLOW_RESOURCES_FOLDER` Deprecated. This is deprecated due to a typo. Use DEFAULT_FLOW_RESOURCES_FOLDER instead.
`static String`	`DEFAULT_CONNECT_APPLICATION_PROPERTIES` Default application properties file path in Connect project.
`static String`	`DEFAULT_CONNECT_GENERATED_TS_DIR` Default generated path for generated TS files.
`static String`	`DEFAULT_CONNECT_JAVA_SOURCE_FOLDER` Default Java source folder for OpenAPI generator.
`static String`	`DEFAULT_CONNECT_OPENAPI_JSON_FILE` Default generated path for OpenAPI spec file.
`static String`	`DEFAULT_FLOW_RESOURCES_FOLDER` Default folder for copying front-end resources present in the classpath jars.
`static String`	`DEFAULT_FRONTEND_DIR` Path of the folder containing application frontend source files, it needs to be relative to the `DEFAULT_NODE_DIR` By default it is `/frontend` in the project folder.
`static String`	`DEFAULT_GENERATED_DIR` Default folder name for flow generated stuff relative to the `TARGET`.
`static String`	`DEFAULT_NODE_DIR` Default folder for the node related content.
`static String`	`DISABLE_CHECK`
`static String`	`EXPORT_CHUNK` The entry-point key used for the exported bundle.
`static String`	`FALLBACK` A key in a Json object for fallback chunk.
`static String`	`FALLBACK_IMPORTS_NAME` Name of the file that contains all application imports, javascript, theme and style annotations which are not discovered by the current scanning strategy (but they are in the project classpath).
`static String`	`FLOW_NPM_PACKAGE_NAME` The NPM package name that will be used for the javascript files present in jar resources that will to be copied to the npm folder so as they are accessible to webpack.
`static String`	`FORM_NPM_PACKAGE_NAME` The NPM package name that will be used for the javascript files present in jar resources that will to be copied to the npm folder so as they are accessible to webpack.
`static String`	`FRONTEND` Default folder used for source and generated folders.
`static String`	`GREEN`
`static String`	`IMPORTS_D_TS_NAME` The TypeScript definitions for the `IMPORTS_NAME` file.
`static String`	`IMPORTS_NAME` Name of the file that contains application imports, javascript, theme and style annotations.
`static String`	`INDEX_HTML` File name of the index.html in client side.
`static String`	`INDEX_JS` File name of the index.js in client side.
`static String`	`INDEX_TS` File name of the index.ts in client side.
`static String`	`INSTALL_NODE_LOCALLY`
`static String`	`JS_MODULES` A key in a Json object for js modules data.
`static String`	`NODE_MODULES` Location for the installed node packages.
`static String`	`PARAM_FRONTEND_DIR` A parameter for overriding the `DEFAULT_FRONTEND_DIR` folder.
`static String`	`PARAM_GENERATED_DIR` A parameter for overriding the `DEFAULT_GENERATED_DIR` folder.
`static String`	`PARAM_IGNORE_VERSION_CHECKS` Set to `true` to ignore node/npm tool version checks.
`static String`	`PARAM_TOKEN_FILE` A parameter informing about the location of the `TOKEN_FILE`.
`static String`	`PROJECT_BASEDIR`
`static String`	`RED`
`static String`	`TARGET` Default target folder for the java project.
`static String`	`TOKEN_FILE` File used to enable npm mode.
`static String`	`WEBPACK_CONFIG` The name of the webpack configuration file.
`static String`	`WEBPACK_GENERATED` The name of the webpack generated configuration file.
`static String`	`WEBPACK_PREFIX_ALIAS` A special prefix used by webpack to map imports placed in the `DEFAULT_FRONTEND_DIR`.
`static String`	`YELLOW`

Method Summary

All Methods
Modifier and Type	Method and Description
`static String`	`commandToString(String baseDir, List<String> command)` Pretty prints a command line order.
`static void`	`console(String format, Object message)` Intentionally send to console instead to log, useful when executing external processes.
`static ProcessBuilder`	`createProcessBuilder(List<String> command)` Creates a process builder for the given list of program and arguments.
`static String`	`getIndexHtmlContent(VaadinService service)` Gets the content of the `frontend/index.html` file which is served by webpack-dev-server in dev-mode and read from classpath in production mode.
`static String`	`getOsName()` Get the Operating System name from the `os.name` system property.
`static String`	`getProjectFrontendDir(DeploymentConfiguration configuration)` Get directory where project's frontend files are located.
`static String`	`getStatsAssetsByChunkName(VaadinService service)` Load the asset chunks from stats.json.
`static String`	`getStatsContent(VaadinService service)` Gets the content of the `stats.json` file produced by webpack.
`static String`	`getStatsHash(VaadinService service)` Get the latest has for the stats file in development mode.
`static String`	`getUnixPath(Path source)` Get path as a String in Unix form.
`static String`	`getUnixRelativePath(Path source, Path target)` Get relative path from a source path to a target path in Unix form.
`static File`	`getVaadinHomeDirectory()` Gets vaadin home directory (`".vaadin"` folder in the user home dir).
`protected static FrontendVersion`	`getVersion(String tool, List<String> versionCommand)`
`static boolean`	`isWebpackConfigFile(File file)` Checks whether the `file` is a webpack configuration file with the expected content (includes a configuration generated by Flow).
`static boolean`	`isWindows()` Check if the current os is Windows.
`static FrontendVersion`	`parseFrontendVersion(String versionString)` Parse the version number of node/npm from version output string.
`static FallbackChunk`	`readFallbackChunk(elemental.json.JsonObject object)` Read fallback chunk data from a json object.
`static String`	`streamToString(InputStream inputStream)` Read a stream and copy the content in a String.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - PROJECT_BASEDIR
```
public static final String PROJECT_BASEDIR
```
    See Also:
    
    Constant Field Values
  - DEFAULT_NODE_DIR
```
public static final String DEFAULT_NODE_DIR
```
    Default folder for the node related content. It's the base directory for Constants.PACKAGE_JSON, WEBPACK_CONFIG, NODE_MODULES. By default it's the project root folder.
    
    See Also:
    
    Constant Field Values
  - NODE_MODULES
```
public static final String NODE_MODULES
```
    Location for the installed node packages. This folder is always considered by node, even though we define extra folders with the NODE_PATH.
    
    See Also:
    
    Constant Field Values
  - FRONTEND
```
public static final String FRONTEND
```
    Default folder used for source and generated folders.
    
    See Also:
    
    Constant Field Values
  - DEFAULT_FRONTEND_DIR
```
public static final String DEFAULT_FRONTEND_DIR
```
    Path of the folder containing application frontend source files, it needs to be relative to the DEFAULT_NODE_DIR By default it is /frontend in the project folder.
    
    See Also:
    
    Constant Field Values
  - WEBPACK_CONFIG
```
public static final String WEBPACK_CONFIG
```
    The name of the webpack configuration file.
    
    See Also:
    
    Constant Field Values
  - WEBPACK_GENERATED
```
public static final String WEBPACK_GENERATED
```
    The name of the webpack generated configuration file.
    
    See Also:
    
    Constant Field Values
  - TARGET
```
public static final String TARGET
```
    Default target folder for the java project.
    
    See Also:
    
    Constant Field Values
  - FLOW_NPM_PACKAGE_NAME
```
public static final String FLOW_NPM_PACKAGE_NAME
```
    The NPM package name that will be used for the javascript files present in jar resources that will to be copied to the npm folder so as they are accessible to webpack.
    
    See Also:
    
    Constant Field Values
  - FORM_NPM_PACKAGE_NAME
```
public static final String FORM_NPM_PACKAGE_NAME
```
    The NPM package name that will be used for the javascript files present in jar resources that will to be copied to the npm folder so as they are accessible to webpack.
    
    See Also:
    
    Constant Field Values
  - DEFAULT_FLOW_RESOURCES_FOLDER
```
public static final String DEFAULT_FLOW_RESOURCES_FOLDER
```
    Default folder for copying front-end resources present in the classpath jars.
    
    See Also:
    
    Constant Field Values
  - DEAULT_FLOW_RESOURCES_FOLDER
```
@Deprecated
public static final String DEAULT_FLOW_RESOURCES_FOLDER
```
    Deprecated. This is deprecated due to a typo. Use DEFAULT_FLOW_RESOURCES_FOLDER instead.
    
    Default folder for copying front-end resources present in the classpath jars.
    
    See Also:
    
    DEFAULT_FLOW_RESOURCES_FOLDER, Constant Field Values
  - DEFAULT_GENERATED_DIR
```
public static final String DEFAULT_GENERATED_DIR
```
    Default folder name for flow generated stuff relative to the TARGET.
    
    See Also:
    
    Constant Field Values
  - IMPORTS_NAME
```
public static final String IMPORTS_NAME
```
    Name of the file that contains application imports, javascript, theme and style annotations. It is also the entry-point for webpack. It is always generated in the DEFAULT_GENERATED_DIR folder.
    
    See Also:
    
    Constant Field Values
  - IMPORTS_D_TS_NAME
```
public static final String IMPORTS_D_TS_NAME
```
    The TypeScript definitions for the IMPORTS_NAME file.
    
    See Also:
    
    Constant Field Values
  - INDEX_HTML
```
public static final String INDEX_HTML
```
    File name of the index.html in client side.
    
    See Also:
    
    Constant Field Values
  - INDEX_TS
```
public static final String INDEX_TS
```
    File name of the index.ts in client side.
    
    See Also:
    
    Constant Field Values
  - INDEX_JS
```
public static final String INDEX_JS
```
    File name of the index.js in client side.
    
    See Also:
    
    Constant Field Values
  - DEFAULT_CONNECT_JAVA_SOURCE_FOLDER
```
public static final String DEFAULT_CONNECT_JAVA_SOURCE_FOLDER
```
    Default Java source folder for OpenAPI generator.
    
    See Also:
    
    Constant Field Values
  - DEFAULT_CONNECT_APPLICATION_PROPERTIES
```
public static final String DEFAULT_CONNECT_APPLICATION_PROPERTIES
```
    Default application properties file path in Connect project.
    
    See Also:
    
    Constant Field Values
  - DEFAULT_CONNECT_OPENAPI_JSON_FILE
```
public static final String DEFAULT_CONNECT_OPENAPI_JSON_FILE
```
    Default generated path for OpenAPI spec file.
    
    See Also:
    
    Constant Field Values
  - DEFAULT_CONNECT_GENERATED_TS_DIR
```
public static final String DEFAULT_CONNECT_GENERATED_TS_DIR
```
    Default generated path for generated TS files.
    
    See Also:
    
    Constant Field Values
  - FALLBACK_IMPORTS_NAME
```
public static final String FALLBACK_IMPORTS_NAME
```
    Name of the file that contains all application imports, javascript, theme and style annotations which are not discovered by the current scanning strategy (but they are in the project classpath). This file is dynamically imported by the IMPORTS_NAME file. It is always generated in the DEFAULT_GENERATED_DIR folder.
    
    See Also:
    
    Constant Field Values
  - PARAM_GENERATED_DIR
```
public static final String PARAM_GENERATED_DIR
```
    A parameter for overriding the DEFAULT_GENERATED_DIR folder.
    
    See Also:
    
    Constant Field Values
  - PARAM_FRONTEND_DIR
```
public static final String PARAM_FRONTEND_DIR
```
    A parameter for overriding the DEFAULT_FRONTEND_DIR folder.
    
    See Also:
    
    Constant Field Values
  - PARAM_IGNORE_VERSION_CHECKS
```
public static final String PARAM_IGNORE_VERSION_CHECKS
```
    Set to true to ignore node/npm tool version checks.
    
    See Also:
    
    Constant Field Values
  - WEBPACK_PREFIX_ALIAS
```
public static final String WEBPACK_PREFIX_ALIAS
```
    A special prefix used by webpack to map imports placed in the DEFAULT_FRONTEND_DIR. e.g. import 'Frontend/foo.js'; references the filefrontend/foo.js.
    
    See Also:
    
    Constant Field Values
  - TOKEN_FILE
```
public static final String TOKEN_FILE
```
    File used to enable npm mode.
    
    See Also:
    
    Constant Field Values
  - CHUNKS
```
public static final String CHUNKS
```
    A key in a Json object for chunks list.
    
    See Also:
    
    Constant Field Values
  - FALLBACK
```
public static final String FALLBACK
```
    A key in a Json object for fallback chunk.
    
    See Also:
    
    Constant Field Values
  - EXPORT_CHUNK
```
public static final String EXPORT_CHUNK
```
    The entry-point key used for the exported bundle.
    
    See Also:
    
    Constant Field Values
  - CSS_IMPORTS
```
public static final String CSS_IMPORTS
```
    A key in a Json object for css imports data.
    
    See Also:
    
    Constant Field Values
  - JS_MODULES
```
public static final String JS_MODULES
```
    A key in a Json object for js modules data.
    
    See Also:
    
    Constant Field Values
  - PARAM_TOKEN_FILE
```
public static final String PARAM_TOKEN_FILE
```
    A parameter informing about the location of the TOKEN_FILE.
    
    See Also:
    
    Constant Field Values
  - INSTALL_NODE_LOCALLY
```
public static final String INSTALL_NODE_LOCALLY
```
    See Also:
    
    Constant Field Values
  - DISABLE_CHECK
```
public static final String DISABLE_CHECK
```
    See Also:
    
    Constant Field Values
  - YELLOW
```
public static final String YELLOW
```
    See Also:
    
    Constant Field Values
  - RED
```
public static final String RED
```
    See Also:
    
    Constant Field Values
  - GREEN
```
public static final String GREEN
```
    See Also:
    
    Constant Field Values
  - BRIGHT_BLUE
```
public static final String BRIGHT_BLUE
```
    See Also:
    
    Constant Field Values
- Method Detail
  - getOsName
```
public static String getOsName()
```
    Get the Operating System name from the os.name system property.
    
    Returns:
    
    operating system name
  - isWindows
```
public static boolean isWindows()
```
    Check if the current os is Windows.
    
    Returns:
    
    true if windows
  - streamToString
```
public static String streamToString(InputStream inputStream)
```
    Read a stream and copy the content in a String.
    
    Parameters:
    
    inputStream - the input stream
    
    Returns:
    
    the string
  - createProcessBuilder
```
public static ProcessBuilder createProcessBuilder(List<String> command)
```
    Creates a process builder for the given list of program and arguments. If the program is defined as an absolute path, then the directory that contains the program is also appended to PATH so that the it can locate related tools.
    
    Parameters:
    
    command - a list with the program and arguments
    
    Returns:
    
    a configured process builder
  - getStatsContent
```
public static String getStatsContent(VaadinService service)
                              throws IOException
```
    Gets the content of the stats.json file produced by webpack.
    
    Parameters:
    
    service - the vaadin service.
    
    Returns:
    
    the content of the file as a string, null if not found.
    
    Throws:
    
    IOException - on error reading stats file.
  - getIndexHtmlContent
```
public static String getIndexHtmlContent(VaadinService service)
                                  throws IOException
```
    Gets the content of the frontend/index.html file which is served by webpack-dev-server in dev-mode and read from classpath in production mode. NOTE: In dev mode, the file content file is fetched via webpack http request. So that we don't need to have a separate index.html's content watcher, auto-reloading will work automatically, like other files managed by webpack in `frontend/` folder.
    
    Parameters:
    
    service - the vaadin service
    
    Returns:
    
    the content of the index html file as a string, null if not found.
    
    Throws:
    
    IOException - on error when reading file
  - getStatsHash
```
public static String getStatsHash(VaadinService service)
                           throws IOException
```
    Get the latest has for the stats file in development mode. This is requested from the webpack-dev-server.
    In production mode and disabled dev server mode an empty string is returned.
    
    Parameters:
    
    service - the Vaadin service.
    
    Returns:
    
    hash string for the stats.json file, empty string if none found
    
    Throws:
    
    IOException - if an I/O error occurs while creating the input stream.
  - getStatsAssetsByChunkName
```
public static String getStatsAssetsByChunkName(VaadinService service)
                                        throws IOException
```
    Load the asset chunks from stats.json. We will only read the file until we have reached the assetsByChunkName json and return that as a json object string.
    
    Parameters:
    
    service - the Vaadin service.
    
    Returns:
    
    json for assetsByChunkName object in stats.json or null if stats.json not found or content not found.
    
    Throws:
    
    IOException - if an I/O error occurs while creating the input stream.
  - getProjectFrontendDir
```
public static String getProjectFrontendDir(DeploymentConfiguration configuration)
```
    Get directory where project's frontend files are located.
    
    Parameters:
    
    configuration - the current deployment configuration
    
    Returns:
    
    DEFAULT_FRONTEND_DIR or value of PARAM_FRONTEND_DIR if it is set.
  - isWebpackConfigFile
```
public static boolean isWebpackConfigFile(File file)
                                   throws IOException
```
    Checks whether the file is a webpack configuration file with the expected content (includes a configuration generated by Flow).
    
    Parameters:
    
    file - a file to check
    
    Returns:
    
    true iff the file exists and includes a generated configuration
    
    Throws:
    
    IOException - if an I/O error occurs while reading the file
  - getUnixRelativePath
```
public static String getUnixRelativePath(Path source,
                                         Path target)
```
    Get relative path from a source path to a target path in Unix form. All the Windows' path separator will be replaced.
    
    Parameters:
    
    source - the source path
    
    target - the target path
    
    Returns:
    
    unix relative path from source to target
  - getUnixPath
```
public static String getUnixPath(Path source)
```
    Get path as a String in Unix form.
    
    Parameters:
    
    source - path to get
    
    Returns:
    
    path as a String in Unix form.
  - readFallbackChunk
```
public static FallbackChunk readFallbackChunk(elemental.json.JsonObject object)
```
    Read fallback chunk data from a json object.
    
    Parameters:
    
    object - json object to read fallback chunk data
    
    Returns:
    
    a fallback chunk data
  - getVersion
```
protected static FrontendVersion getVersion(String tool,
                                            List<String> versionCommand)
                                     throws FrontendUtils.UnknownVersionException
```
    Throws:
    
    FrontendUtils.UnknownVersionException
  - parseFrontendVersion
```
public static FrontendVersion parseFrontendVersion(String versionString)
                                            throws IOException
```
    Parse the version number of node/npm from version output string.
    
    Parameters:
    
    versionString - string containing version output, typically produced by tool --version
    
    Returns:
    
    FrontendVersion of versionString
    
    Throws:
    
    IOException - if parsing fails
  - getVaadinHomeDirectory
```
public static File getVaadinHomeDirectory()
```
    Gets vaadin home directory (".vaadin" folder in the user home dir).
    The directory is created if it's doesn't exist.
    
    Returns:
    
    a vaadin home directory
  - commandToString
```
public static String commandToString(String baseDir,
                                     List<String> command)
```
    Pretty prints a command line order. It split in lines adapting to 80 columns, and allowing copy and paste in console. It also removes the current directory to avoid security issues in log files.
    
    Parameters:
    
    baseDir - the current directory
    
    command - the command and it's arguments
    
    Returns:
    
    the string for printing in logs
  - console
```
public static void console(String format,
                           Object message)
```
    Intentionally send to console instead to log, useful when executing external processes.
    
    Parameters:
    
    format - Format of the line to send to console, it must contain a `%s` outlet for the message
    
    message - the string to show

com.vaadin.flow.server.frontend.

Class FrontendUtils

Nested Class Summary

Field Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

PROJECT_BASEDIR

DEFAULT_NODE_DIR

NODE_MODULES

FRONTEND

DEFAULT_FRONTEND_DIR

WEBPACK_CONFIG

WEBPACK_GENERATED

TARGET

FLOW_NPM_PACKAGE_NAME

FORM_NPM_PACKAGE_NAME

DEFAULT_FLOW_RESOURCES_FOLDER

DEAULT_FLOW_RESOURCES_FOLDER

DEFAULT_GENERATED_DIR

IMPORTS_NAME

IMPORTS_D_TS_NAME

INDEX_HTML

INDEX_TS

INDEX_JS

DEFAULT_CONNECT_JAVA_SOURCE_FOLDER

DEFAULT_CONNECT_APPLICATION_PROPERTIES

DEFAULT_CONNECT_OPENAPI_JSON_FILE

DEFAULT_CONNECT_GENERATED_TS_DIR

FALLBACK_IMPORTS_NAME

PARAM_GENERATED_DIR

PARAM_FRONTEND_DIR

PARAM_IGNORE_VERSION_CHECKS

WEBPACK_PREFIX_ALIAS

TOKEN_FILE

CHUNKS

FALLBACK

EXPORT_CHUNK

CSS_IMPORTS

JS_MODULES

PARAM_TOKEN_FILE

INSTALL_NODE_LOCALLY

DISABLE_CHECK

YELLOW

RED

GREEN

BRIGHT_BLUE

Method Detail

getOsName

isWindows

streamToString

createProcessBuilder

getStatsContent

getIndexHtmlContent

getStatsHash

getStatsAssetsByChunkName

getProjectFrontendDir

isWebpackConfigFile

getUnixRelativePath

getUnixPath

readFallbackChunk

getVersion

parseFrontendVersion

getVaadinHomeDirectory

commandToString

console