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一 HttpEntity的类型
1 BasicHttpEntity
代表底层流的基本实体。通常是在http报文中获取的实体。他只有一个空参的构造方法。刚创建时没有内容，长度为负值。需要通过两个方法，把值赋进去。
-
/** -
* BasicHttpEntity -
* @throws IOException -
*/ -
public static void testBasicHttpEntity() throws IOException{
-
InputStream is = null; -
//BasicHttpEntity这类就是一个输入流的内容包装类，包装内容的相关的编码格式，长度等 -
BasicHttpEntity entity = new BasicHttpEntity(); -
//设置内容 -
entity.setContent(is); -
//设置长度 -
entity.setContentLength(is.available()); -
//没搞懂chunked这个属性啥意思 -
entity.setChunked(false); -
}
2 ByteArrayEntity
是自我包含的，可重复获得使用的，从指定的字节数组中取出内容的实体。字节数组是这个实体的构造方法的参数。
-
/** -
* ByteArrayEntity -
* @throws IOException -
*/ -
public static void testByteArrayEntity() throws IOException{
-
ByteArrayEntity entity = new ByteArrayEntity("内容".getBytes()); -
ByteArrayInputStream is = (ByteArrayInputStream) entity.getContent(); -
//上面这行代码返回的其实是一个ByteArrayInputStream对象 -
/*public InputStream getContent() {
-
return new ByteArrayInputStream(this.b, this.off, this.len); -
}*/ -
}
3 StringEntity
是自我包含的可重复的实体。通过String创建的实体。有两个构造方法，一个是自Sring为参数的构造方法，一个是以String和字符编码为参数的构造方法。
-
/** -
* StringEntity -
* @throws IOException -
*/ -
public static void testStringEntity() throws IOException{
-
StringBuilder sb = new StringBuilder(); -
//获取系统的信息集合，这个集合是不可以修改的 -
Map<String, String> nev = System.getenv(); -
for(Entry<String, String> entry : nev.entrySet()){
-
sb.append(entry.getKey()).append("=") -
.append(entry.getValue()).append("\n"); -
} -
String content = sb.toString(); -
System.out.println(content); -
//创建只带字符串参数的 -
StringEntity entity = new StringEntity(content); -
//创建带字符创参数和字符编码的 -
StringEntity entity2 = new StringEntity(content, "UTF-8"); -
}
4 InputreamEntity
是流式不可以重复的实体。构造方法是InputStream 和内容长度，内容长度是输入流的长度。
-
/** -
* InputStreamEntity -
* @throws IOException -
*/ -
public static void testInputStreamEntity() throws IOException{
-
InputStream is = null; -
//InputStreamEntity严格是对内容和长度相匹配的。用法和BasicHttpEntity类似 -
InputStreamEntity entity = new InputStreamEntity(is, is.available()); -
}
5 FileEntity
自我包含式，可以重复的实体。参数传入文件和文件类型。
-
/** -
* FileEntity -
* @throws IOException -
*/ -
public static void testFileEntity() throws IOException{
-
FileEntity entity = new FileEntity(new File(""), ContentType.APPLICATION_FORM_URLENCODED); -
FileEntity entity2 = new FileEntity(new File(""), "application/java-achive"); -
}
6 EntityTemplete
从ContentProducer接口接受内容的实体。在ContentProducer的实现类中写入想要写入的内容。
-
/** -
* EntityTemplate -
* @throws IOException -
*/ -
public static void testEntityTemplate() throws IOException{
-
ContentProducer producer = new ContentProducer() {
-
@Override -
public void writeTo(OutputStream outstream) throws IOException {
-
outstream.write("这是什么东东》。".getBytes()); -
} -
}; -
EntityTemplate entity = new EntityTemplate(producer); -
entity.writeTo(System.out); -
}
7 HttpEntityWrapper
这个是创建被包装实体的基类，有被包装实体的引用。相当于实体的代理类，被包装实体是他的一个属性。下面是这个类的源码：
-
/* -
* ==================================================================== -
* Licensed to the Apache Software Foundation (ASF) under one -
* or more contributor license agreements. See the NOTICE file -
* distributed with this work for additional information -
* regarding copyright ownership. The ASF licenses this file -
* to you under the Apache License, Version 2.0 (the -
* "License"); you may not use this file except in compliance -
* with the License. You may obtain a copy of the License at -
* -
* http://www.apache.org/licenses/LICENSE-2.0 -
* -
* Unless required by applicable law or agreed to in writing, -
* software distributed under the License is distributed on an -
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY -
* KIND, either express or implied. See the License for the -
* specific language governing permissions and limitations -
* under the License. -
* ==================================================================== -
* -
* This software consists of voluntary contributions made by many -
* individuals on behalf of the Apache Software Foundation. For more -
* information on the Apache Software Foundation, please see -
* <http://www.apache.org/>. -
* -
*/ -
package org.apache.http.entity; -
import java.io.IOException; -
import java.io.InputStream; -
import java.io.OutputStream; -
import org.apache.http.Header; -
import org.apache.http.HttpEntity; -
import org.apache.http.annotation.NotThreadSafe; -
/** -
* Base class for wrapping entities. -
* Keeps a {@link #wrappedEntity wrappedEntity} and delegates all -
* calls to it. Implementations of wrapping entities can derive -
* from this class and need to override only those methods that -
* should not be delegated to the wrapped entity. -
* -
* @since 4.0 -
*/ -
@NotThreadSafe -
public class HttpEntityWrapper implements HttpEntity {
-
/** The wrapped entity. */ -
protected HttpEntity wrappedEntity; -
/** -
* Creates a new entity wrapper. -
* -
* @param wrapped the entity to wrap, not null -
* @throws IllegalArgumentException if wrapped is null -
*/ -
public HttpEntityWrapper(HttpEntity wrapped) {
-
super(); -
if (wrapped == null) {
-
throw new IllegalArgumentException -
("wrapped entity must not be null"); -
} -
wrappedEntity = wrapped; -
} // constructor -
public boolean isRepeatable() {
-
return wrappedEntity.isRepeatable(); -
} -
public boolean isChunked() {
-
return wrappedEntity.isChunked(); -
} -
public long getContentLength() {
-
return wrappedEntity.getContentLength(); -
} -
public Header getContentType() {
-
return wrappedEntity.getContentType(); -
} -
public Header getContentEncoding() {
-
return wrappedEntity.getContentEncoding(); -
} -
public InputStream getContent() -
throws IOException {
-
return wrappedEntity.getContent(); -
} -
public void writeTo(OutputStream outstream) -
throws IOException {
-
wrappedEntity.writeTo(outstream); -
} -
public boolean isStreaming() {
-
return wrappedEntity.isStreaming(); -
} -
/** -
* @deprecated (4.1) Either use {@link #getContent()} and call {@link java.io.InputStream#close()} on that; -
* otherwise call {@link #writeTo(OutputStream)} which is required to free the resources. -
*/ -
@Deprecated -
public void consumeContent() throws IOException {
-
wrappedEntity.consumeContent(); -
} -
}
8 BufferedHttpEntity
是HttpEntityWarpper的子类，可以把不可以重复的实体，实现成可以重复的实体。它从提供的实体中读取内容，缓存到内容中。源码如下：
-
/* -
* ==================================================================== -
* Licensed to the Apache Software Foundation (ASF) under one -
* or more contributor license agreements. See the NOTICE file -
* distributed with this work for additional information -
* regarding copyright ownership. The ASF licenses this file -
* to you under the Apache License, Version 2.0 (the -
* "License"); you may not use this file except in compliance -
* with the License. You may obtain a copy of the License at -
* -
* http://www.apache.org/licenses/LICENSE-2.0 -
* -
* Unless required by applicable law or agreed to in writing, -
* software distributed under the License is distributed on an -
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY -
* KIND, either express or implied. See the License for the -
* specific language governing permissions and limitations -
* under the License. -
* ==================================================================== -
* -
* This software consists of voluntary contributions made by many -
* individuals on behalf of the Apache Software Foundation. For more -
* information on the Apache Software Foundation, please see -
* <http://www.apache.org/>. -
* -
*/ -
package org.apache.http.entity; -
import java.io.ByteArrayInputStream; -
import java.io.IOException; -
import java.io.InputStream; -
import java.io.OutputStream; -
import org.apache.http.HttpEntity; -
import org.apache.http.annotation.NotThreadSafe; -
import org.apache.http.util.EntityUtils; -
/** -
* A wrapping entity that buffers it content if necessary. -
* The buffered entity is always repeatable. -
* If the wrapped entity is repeatable itself, calls are passed through. -
* If the wrapped entity is not repeatable, the content is read into a -
* buffer once and provided from there as often as required. -
* -
* @since 4.0 -
*/ -
@NotThreadSafe -
public class BufferedHttpEntity extends HttpEntityWrapper {
-
private final byte[] buffer; -
/** -
* Creates a new buffered entity wrapper. -
* -
* @param entity the entity to wrap, not null -
* @throws IllegalArgumentException if wrapped is null -
*/ -
public BufferedHttpEntity(final HttpEntity entity) throws IOException {
-
super(entity); -
if (!entity.isRepeatable() || entity.getContentLength() < 0) {
-
this.buffer = EntityUtils.toByteArray(entity); -
} else {
-
this.buffer = null; -
} -
} -
@Override -
public long getContentLength() {
-
if (this.buffer != null) {
-
return this.buffer.length; -
} else {
-
return wrappedEntity.getContentLength(); -
} -
} -
@Override -
public InputStream getContent() throws IOException {
-
if (this.buffer != null) {
-
return new ByteArrayInputStream(this.buffer); -
} else {
-
return wrappedEntity.getContent(); -
} -
} -
/** -
* Tells that this entity does not have to be chunked. -
* -
* @return <code>false</code> -
*/ -
@Override -
public boolean isChunked() {
-
return (buffer == null) && wrappedEntity.isChunked(); -
} -
/** -
* Tells that this entity is repeatable. -
* -
* @return <code>true</code> -
*/ -
@Override -
public boolean isRepeatable() {
-
return true; -
} -
@Override -
public void writeTo(final OutputStream outstream) throws IOException {
-
if (outstream == null) {
-
throw new IllegalArgumentException("Output stream may not be null"); -
} -
if (this.buffer != null) {
-
outstream.write(this.buffer); -
} else {
-
wrappedEntity.writeTo(outstream); -
} -
} -
// non-javadoc, see interface HttpEntity -
@Override -
public boolean isStreaming() {
-
return (buffer == null) && wrappedEntity.isStreaming(); -
} -
} // class BufferedHttpEntity
二 HttpEntity 的使用
1 HttpEntity实体即可以使流也可以使字符串形式。具体有什么用法看他的方法解释：
-
package com.scl.base; -
import java.io.IOException; -
import java.io.UnsupportedEncodingException; -
import org.apache.http.HttpEntity; -
import org.apache.http.ParseException; -
import org.apache.http.entity.StringEntity; -
import org.apache.http.util.EntityUtils; -
public class HttpClientDemo06 {
-
/** -
* @param args -
*/ -
public static void main(String[] args) {
-
try {
-
HttpEntity entity = new StringEntity("这一个字符串实体", "UTF-8"); -
//内容类型 -
System.out.println(entity.getContentType()); -
//内容的编码格式 -
System.out.println(entity.getContentEncoding()); -
//内容的长度 -
System.out.println(entity.getContentLength()); -
//把内容转成字符串 -
System.out.println(EntityUtils.toString(entity)); -
//内容转成字节数组 -
System.out.println(EntityUtils.toByteArray(entity).length); -
//还有个直接获得流 -
//entity.getContent(); -
} catch (UnsupportedEncodingException e) {
-
throw new RuntimeException(e); -
} catch (ParseException e) {
-
} catch (IOException e) {
-
} -
} -
}
2 对于实体的资源使用完之后要适当的回收资源，特别是对于流实体。例子代码如下:
-
public static void test() throws IllegalStateException, IOException{
-
HttpResponse response = null; -
HttpEntity entity = response.getEntity(); -
if(entity!=null){
-
InputStream is = entity.getContent(); -
try{
-
//做一些操作 -
}finally{
-
//最后别忘了关闭应该关闭的资源，适当的释放资源 -
if(is != null){
-
is.close(); -
} -
//这个方法也可以把底层的流给关闭了 -
EntityUtils.consume(entity); -
//下面是这方法的源码 -
/*public static void consume(final HttpEntity entity) throws IOException {
-
if (entity == null) {
-
return; -
} -
if (entity.isStreaming()) {
-
InputStream instream = entity.getContent(); -
if (instream != null) {
-
instream.close(); -
} -
} -
}*/ -
} -
}
FROM: http://blog.csdn.net/athenamax/article/details/8185043http://blog.csdn.net/athenamax/article/details/8185041
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