使用HttpClient,我们可以执行分段上传,即我们可以在
较小的部分中上传较大的对象.在本章中,我们通过上传一个简单的文本文件来演示HTTP客户端中的分段上传.
通常,任何分段上传都包含三个部分.
启动上传
上传对象部分
完成分段上传
对于使用HttpClient进行分段上传,我们需要遵循以下内容步骤&减去;
创建一个多部分构建器.
添加所需的部分.
完成构建并获得多部分HttpEntity.
通过设置上述多部分实体来构建请求.
执行请求.
以下是使用HttpClient库上传多部分实体的步骤.
HttpClients 类的 createDefault()方法返回一个类 CloseableHttpClient 的对象,它是HttpClient接口的基本实现.使用此方法,创建一个HttpClient对象 :
//Creating CloseableHttpClient object CloseableHttpClient httpclient = HttpClients.createDefault();
FileBody 类表示二进制正文部分由文件支持.通过传递文件对象和表示内容类型的 ContentType 对象来实例化此类.
//Creating a File object File file = new File("sample.txt"); //Creating the FileBody object FileBody filebody = new FileBody(file, ContentType.DEFAULT_BINARY);
MultipartEntityBuilder 类用于构建多部分 HttpEntity 对象.使用 create()方法(同一类)创建其对象.
//Creating the MultipartEntityBuilder MultipartEntityBuilder entitybuilder = MultipartEntityBuilder.create();
A MultipartEntityBuilder 有三种模式:STRICT, RFC6532和BROWSER_COMPATIBLE.使用 setMode()方法将其设置为所需模式.
//Setting the mode entitybuilder.setMode(HttpMultipartMode.BROWSER_COMPATIBLE);
使用方法 addTextBody() ,addPart()和 addBinaryBody(),您可以将简单的文本,文件,流和其他对象添加到 MultipartBuilder .使用这些方法添加所需内容.
//Adding text entitybuilder.addTextBody("sample_text", "This is the text part of our file"); //Adding a file entitybuilder.addBinaryBody("image", new File("logo.png"));
您可以使用将所有这些部分构建到单个实体 MultipartEntityBuilder 类的build()方法.使用此方法,将所有部件构建为单个 HttpEntity .
//Building a single entity using the parts HttpEntity mutiPartHttpEntity = entityBuilder.build();
使用类 RequestBuilder 来构建通过向其添加参数来请求.如果请求是PUT或POST类型,它会将参数作为URL编码实体添加到请求中.
使用 post()创建一个RequestBuilder对象(类型为POST) 方法.并将您想要发送请求的Uri
作为参数传递.
//Building the post request object RequestBuilder reqbuilder = RequestBuilder.post("http://httpbin.org/post");
使用以下方法将上面创建的多部分实体设置为RequestBuilder RequestBuilder 类的 setEntity()方法.
//Setting the entity object to the RequestBuilder reqbuilder.setEntity(mutiPartHttpEntity);
使用RequestBuilder 类的build()方法构建 HttpUriRequest 请求对象
//Executing the request HttpResponse httpresponse = httpclient.execute(multipartRequest);
使用 execute()方法,执行上一步中构建的请求(绕过请求作为此方法的参数).
//执行请求 HttpResponse httpresponse = httpclient.execute(multipartRequest);
以下示例演示了如何使用HttpClient库发送多部分请求.在此示例中,我们尝试发送由文件支持的多部分请求.
import org.apache.http.HttpEntity; import org.apache.http.HttpResponse; import org.apache.http.client.methods.HttpUriRequest; import org.apache.http.client.methods.RequestBuilder; import org.apache.http.entity.ContentType; import org.apache.http.entity.mime.HttpMultipartMode; import org.apache.http.entity.mime.MultipartEntityBuilder; import org.apache.http.entity.mime.content.FileBody; import org.apache.http.impl.client.CloseableHttpClient; import org.apache.http.impl.client.HttpClients; import org.apache.http.util.EntityUtils; import java.io.File; import java.io.IOException; import java.net.URISyntaxException; public class MultipartUploadExample { public static void main(String args[]) throws Exception{ //Creating CloseableHttpClient object CloseableHttpClient httpclient = HttpClients.createDefault(); //Creating a file object File file = new File("sample.txt"); //Creating the FileBody object FileBody filebody = new FileBody(file, ContentType.DEFAULT_BINARY); //Creating the MultipartEntityBuilder MultipartEntityBuilder entitybuilder = MultipartEntityBuilder.create(); //Setting the mode entitybuilder.setMode(HttpMultipartMode.BROWSER_COMPATIBLE); //Adding text entitybuilder.addTextBody("sample_text", "This is the text part of our file"); //Adding a file entitybuilder.addBinaryBody("image", new File("logo.png")); //Building a single entity using the parts HttpEntity mutiPartHttpEntity = entitybuilder.build(); //Building the RequestBuilder request object RequestBuilder reqbuilder = RequestBuilder.post("http://httpbin.org/post"); //Set the entity object to the RequestBuilder reqbuilder.setEntity(mutiPartHttpEntity); //Building the request HttpUriRequest multipartRequest = reqbuilder.build(); //Executing the request HttpResponse httpresponse = httpclient.execute(multipartRequest); //Printing the status and the contents of the response System.out.println(EntityUtils.toString(httpresponse.getEntity())); System.out.println(httpresponse.getStatusLine()); } }
执行时,上述程序生成以下输出 :
{ "args": {}, "data": "", "files": { "image": "data:application/octets66PohrH3IWNk1FzpohfdXPIfv9X3490FGcuXsHn9X0piCwomF/xdgADZ9GsfSyvLYAAAAAE lFTkSuQmCC" }, "form": { "sample_text": "This is the text part of our file" }, "headers": { "Accept-Encoding": "gzip,deflate", "Connection": "close", "Content-Length": "11104", "Content-Type": "multipart/form-data; boundary=UFJbPHT7mTwpVq70LpZgCi5I2nvxd1g-I8Rt", "Host": "httpbin.org", "User-Agent": "Apache-HttpClient/4.5.6 (Java/1.8.0_91)" }, "json": null, "origin": "117.216.245.180", "url": "http://httpbin.org/post" } HTTP/1.1 200 OK