DownloadSession

java.lang.Object
- ohos.miscservices.download.DownloadSession

```
public class DownloadSession
extends Object
```
Defines an HTTP or HTTPS download session as a DownloadSession object and provides management interfaces, such as starting, pausing, resuming, and deleting a session, and querying session details.
Note that applications must obtain the ohos.permission.INTERNET permission to use the interfaces.

从以下版本开始:

1

SystemCapability

SystemCapability.Miscservices#DOWNLOAD

嵌套类概要

嵌套类
限定符和类型类说明

static class DownloadSession.DownloadInfo
Provides methods for obtaining download session information and status.

嵌套类
限定符和类型	类	说明
`static class`	`DownloadSession.DownloadInfo`	Provides methods for obtaining download session information and status.

字段概要

字段
限定符和类型	字段	说明
`static int`	`ERROR_CANNOT_RESUME`	Indicates that the download cannot be resumed for some temporary errors.
`static int`	`ERROR_DEVICE_NOT_FOUND`	Indicates that no storage device, such as an SD card, is found.
`static int`	`ERROR_FILE_ALREADY_EXISTS`	Indicates that files to be downloaded already exist, and that the download session cannot overwrite the existing files.
`static int`	`ERROR_FILE_ERROR`	Indicates that a file operation fails.
`static int`	`ERROR_HTTP_DATA_ERROR`	Indicates that the HTTP transmission fails.
`static int`	`ERROR_INSUFFICIENT_SPACE`	Indicates insufficient storage space.
`static int`	`ERROR_TOO_MANY_REDIRECTS`	Indicates an error caused by too many network redirections.
`static int`	`ERROR_UNHANDLED_HTTP_CODE`	Indicates an HTTP code that cannot be identified.
`static int`	`ERROR_UNKNOWN`	Indicates an undefined error.
`static int`	`PAUSED_QUEUED_FOR_WIFI`	Indicates that the download is paused and waiting for a WLAN connection, because the file size exceeds the maximum allowed for a session using the cellular network.
`static int`	`PAUSED_UNKNOWN`	Indicates that the download is paused for some reasons.
`static int`	`PAUSED_WAITING_FOR_NETWORK`	Indicates that the download is paused due to a network problem, for example, network disconnection.
`static int`	`PAUSED_WAITING_TO_RETRY`	Indicates that a network error occurs, and the download session will be retried.
`static int`	`SESSION_FAILED`	Indicates that the download session has failed and will not be retried.
`static int`	`SESSION_PAUSED`	Indicates that the download session has been paused.
`static int`	`SESSION_PENDING`	Indicates that the download session is being scheduled.
`static int`	`SESSION_RUNNING`	Indicates that the download session is in progress.
`static int`	`SESSION_SUCCESSFUL`	Indicates that the download session is completed.

构造器概要

构造器
构造器	说明
`DownloadSession(Context context, DownloadConfig config)`	A constructor used to create a `DownloadSession` object based on a specified `DownloadConfig` object.
`DownloadSession(Context context, Uri uri)`	A constructor used to create a `DownloadSession` object based on a specified HTTP URI.

方法概要

所有方法实例方法具体方法
限定符和类型	方法	说明
`boolean`	`addListener(IDownloadListener listener)`	Adds a download session listener, which is defined in `IDownloadListener`.
`boolean`	`attach(long id)`	Associates a newly created download session with a specified ID.
`MessageParcel`	`openDownloadedFile()`	Opens a downloaded file.
`boolean`	`pause()`	Pauses a download session.
`DownloadSession.DownloadInfo`	`query()`	Queries download information of a session, which is defined in `DownloadSession.DownloadInfo`.
`String`	`queryMimeType()`	Queries the MIME type of the download file.
`boolean`	`remove()`	Deletes a download session and the downloaded files.
`boolean`	`removeListener(IDownloadListener listener)`	Deletes a download session listener, which is defined in `IDownloadListener`.
`boolean`	`resume()`	Resumes a paused download session.
`long`	`start()`	Starts a download session.

从类继承的方法 java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- 字段详细资料
  - ERROR_CANNOT_RESUME
```
public static final int ERROR_CANNOT_RESUME
```
    Indicates that the download cannot be resumed for some temporary errors.
    
    从以下版本开始:
    
    1
    
    另请参阅:
    
    常量字段值
  - ERROR_DEVICE_NOT_FOUND
```
public static final int ERROR_DEVICE_NOT_FOUND
```
    Indicates that no storage device, such as an SD card, is found.
    
    从以下版本开始:
    
    1
    
    另请参阅:
    
    常量字段值
  - ERROR_FILE_ALREADY_EXISTS
```
public static final int ERROR_FILE_ALREADY_EXISTS
```
    Indicates that files to be downloaded already exist, and that the download session cannot overwrite the existing files.
    
    从以下版本开始:
    
    1
    
    另请参阅:
    
    常量字段值
  - ERROR_FILE_ERROR
```
public static final int ERROR_FILE_ERROR
```
    Indicates that a file operation fails. For example, a storage device fails to be accessed.
    
    从以下版本开始:
    
    1
    
    另请参阅:
    
    常量字段值
  - ERROR_HTTP_DATA_ERROR
```
public static final int ERROR_HTTP_DATA_ERROR
```
    Indicates that the HTTP transmission fails.
    
    从以下版本开始:
    
    1
    
    另请参阅:
    
    常量字段值
  - ERROR_INSUFFICIENT_SPACE
```
public static final int ERROR_INSUFFICIENT_SPACE
```
    Indicates insufficient storage space.
    
    从以下版本开始:
    
    1
    
    另请参阅:
    
    常量字段值
  - ERROR_TOO_MANY_REDIRECTS
```
public static final int ERROR_TOO_MANY_REDIRECTS
```
    Indicates an error caused by too many network redirections.
    
    从以下版本开始:
    
    1
    
    另请参阅:
    
    常量字段值
  - ERROR_UNHANDLED_HTTP_CODE
```
public static final int ERROR_UNHANDLED_HTTP_CODE
```
    Indicates an HTTP code that cannot be identified.
    
    从以下版本开始:
    
    1
    
    另请参阅:
    
    常量字段值
  - ERROR_UNKNOWN
```
public static final int ERROR_UNKNOWN
```
    Indicates an undefined error.
    
    从以下版本开始:
    
    1
    
    另请参阅:
    
    常量字段值
  - PAUSED_QUEUED_FOR_WIFI
```
public static final int PAUSED_QUEUED_FOR_WIFI
```
    Indicates that the download is paused and waiting for a WLAN connection, because the file size exceeds the maximum allowed for a session using the cellular network.
    
    从以下版本开始:
    
    1
    
    另请参阅:
    
    常量字段值
  - PAUSED_UNKNOWN
```
public static final int PAUSED_UNKNOWN
```
    Indicates that the download is paused for some reasons.
    
    从以下版本开始:
    
    1
    
    另请参阅:
    
    常量字段值
  - PAUSED_WAITING_FOR_NETWORK
```
public static final int PAUSED_WAITING_FOR_NETWORK
```
    Indicates that the download is paused due to a network problem, for example, network disconnection.
    
    从以下版本开始:
    
    1
    
    另请参阅:
    
    常量字段值
  - PAUSED_WAITING_TO_RETRY
```
public static final int PAUSED_WAITING_TO_RETRY
```
    Indicates that a network error occurs, and the download session will be retried.
    
    从以下版本开始:
    
    1
    
    另请参阅:
    
    常量字段值
  - SESSION_FAILED
```
public static final int SESSION_FAILED
```
    Indicates that the download session has failed and will not be retried.
    
    从以下版本开始:
    
    1
    
    另请参阅:
    
    常量字段值
  - SESSION_PAUSED
```
public static final int SESSION_PAUSED
```
    Indicates that the download session has been paused.
    
    从以下版本开始:
    
    1
    
    另请参阅:
    
    常量字段值
  - SESSION_PENDING
```
public static final int SESSION_PENDING
```
    Indicates that the download session is being scheduled.
    
    从以下版本开始:
    
    1
    
    另请参阅:
    
    常量字段值
  - SESSION_RUNNING
```
public static final int SESSION_RUNNING
```
    Indicates that the download session is in progress.
    
    从以下版本开始:
    
    1
    
    另请参阅:
    
    常量字段值
  - SESSION_SUCCESSFUL
```
public static final int SESSION_SUCCESSFUL
```
    Indicates that the download session is completed.
    
    从以下版本开始:
    
    1
    
    另请参阅:
    
    常量字段值
- 构造器详细资料
  - DownloadSession
```
public DownloadSession(Context context,
                       DownloadConfig config)
```
    A constructor used to create a DownloadSession object based on a specified DownloadConfig object.
    
    参数:
    
    context - Indicates the application context.
    
    config - Indicates a DownloadConfig object.
    
    另请参阅:
    
    attach(long)
  - DownloadSession
```
public DownloadSession(Context context,
                       Uri uri)
```
    A constructor used to create a DownloadSession object based on a specified HTTP URI.
    
    参数:
    
    context - Indicates the application context.
    
    uri - Indicates an HTTP URI referenced to the file to download.
    
    抛出:
    
    NullPointerException - Throws this exception if the URI is null.
    
    IllegalArgumentException - Throws this exception if the URI is not in the HTTP or HTTPS format.
- 方法详细资料
  - attach
```
public boolean attach(long id)
```
    Associates a newly created download session with a specified ID.
    Applications should save download session IDs returned by start() to local storage. After the application restarts, create a download session and use this method to associate it with a stored session ID.
    
    参数:
    
    id - Indicates a download session ID.
    
    返回:
    
    Returns true if the session is associated with the ID; returns false otherwise. The association may fail because the download session does not exist or it has been started.
  - start
```
public long start()
```
    Starts a download session.
    If the session is successfully started, the session ID is returned. Keep the ID properly. It will be used for the download session after the application restarts.
    The ohos.permission.INTERNET permission is required to use this method.
    
    返回:
    
    Returns the download session ID if the session is started; returns -1 otherwise.
    
    另请参阅:
    
    attach(long)
  - remove
```
public boolean remove()
```
    Deletes a download session and the downloaded files.
    
    返回:
    
    Returns true if the session is deleted; returns false otherwise.
  - pause
```
public boolean pause()
```
    Pauses a download session.
    
    返回:
    
    Returns true if the download is paused; returns false otherwise.
    
    另请参阅:
    
    resume()
  - resume
```
public boolean resume()
```
    Resumes a paused download session.
    Only if the server providing files supports resumable upload, the download session can be resumed.
    
    返回:
    
    Returns true if the download is resumed; returns false otherwise.
    
    另请参阅:
    
    pause()
  - query
```
public DownloadSession.DownloadInfo query()
```
    Queries download information of a session, which is defined in DownloadSession.DownloadInfo.
    
    返回:
    
    Returns the download information if found; returns null otherwise.
    
    另请参阅:
    
    DownloadSession.DownloadInfo
  - addListener
```
public boolean addListener(IDownloadListener listener)
```
    Adds a download session listener, which is defined in IDownloadListener.
    The ohos.permission.INTERNET permission is required to use this method.
    
    参数:
    
    listener - Indicates the listener to be added.
    
    返回:
    
    Returns true if the listener is added, returns false otherwise.
  - removeListener
```
public boolean removeListener(IDownloadListener listener)
```
    Deletes a download session listener, which is defined in IDownloadListener.
    The ohos.permission.INTERNET permission is required to use this method.
    
    参数:
    
    listener - Indicates the listener to be deleted.
    
    返回:
    
    Returns true if the listener is deleted, returns false otherwise.
  - openDownloadedFile
```
public MessageParcel openDownloadedFile()
                                 throws FileNotFoundException
```
    Opens a downloaded file.
    
    返回:
    
    Returns a downloaded file opened as MessageParcel.
    
    抛出:
    
    FileNotFoundException - Throws this exception if the file cannot be opened.
  - queryMimeType
```
public String queryMimeType()
```
    Queries the MIME type of the download file.
    
    返回:
    
    Returns the MIME type if the file is successfully downloaded; returns null otherwise.
    
    从以下版本开始:
    
    4

类 DownloadSession

嵌套类概要

字段概要

构造器概要

方法概要

从类继承的方法 java.lang.Object

字段详细资料

ERROR_CANNOT_RESUME

ERROR_DEVICE_NOT_FOUND

ERROR_FILE_ALREADY_EXISTS

ERROR_FILE_ERROR

ERROR_HTTP_DATA_ERROR

ERROR_INSUFFICIENT_SPACE

ERROR_TOO_MANY_REDIRECTS

ERROR_UNHANDLED_HTTP_CODE

ERROR_UNKNOWN

PAUSED_QUEUED_FOR_WIFI

PAUSED_UNKNOWN

PAUSED_WAITING_FOR_NETWORK

PAUSED_WAITING_TO_RETRY

SESSION_FAILED

SESSION_PAUSED

SESSION_PENDING

SESSION_RUNNING

SESSION_SUCCESSFUL

构造器详细资料

DownloadSession

DownloadSession

方法详细资料

attach

start

remove

pause

resume

query

addListener

removeListener

openDownloadedFile

queryMimeType