HttpEntity型別有哪些
代表底層流的基本實體。通常是在http報文中獲取的實體。他只有一個空參的構造方法。
剛建立時沒有內容，長度為負值。需要通過兩個方法，把值賦進去。
/**
* BasicHttpEntity
* @throws IOException
*/
public static void testBasicHttpEntity() throws IOException{
InputStream is = null;
//BasicHttpEntity這類就是一個輸入流的內容包裝類，包裝內容的相關的編碼格式，長度等
BasicHttpEntity entity = new BasicHttpEntity();
//設定內容
entity.setContent(is);
//設定長度
entity.setContentLength(is.available());
//沒搞懂chunked這個屬性啥意思
entity.setChunked(false);
}
ByteArrayEntity
是自我包含的，可重複獲得使用的，從指定的位元組陣列中取出內容的實體。
位元組陣列是這個實體的構造方法的引數
/**
* ByteArrayEntity
* @throws IOException
*/
public static void testByteArrayEntity() throws IOException{
ByteArrayEntity entity = new ByteArrayEntity("內容".getBytes());
ByteArrayInputStream is = (ByteArrayInputStream) entity.getContent();
//上面這行程式碼返回的其實是一個ByteArrayInputStream物件
/*public InputStream getContent() {
return new ByteArrayInputStream(this.b, this.off, this.len);
}*/
}
StringEntity
是自我包含的可重複的實體。通過String建立的實體
有兩個構造方法，一個是自Sring為引數的構造方法，一個是以String和字元編碼為引數的構造方法。
/**
* StringEntity
* @throws IOException
*/
public static void testStringEntity() throws IOException{
StringBuilder sb = new StringBuilder();
//獲取系統的資訊集合，這個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);
//建立只帶字串引數的
StringEntity entity = new StringEntity(content);
//建立帶字元創引數和字元編碼的
StringEntity entity2 = new StringEntity(content, "UTF-8");
}
InputreamEntity
是流式不可以重複的實體。構造方法是InputStream 和內容長度，內容長度是輸入流的長度
/**
* InputStreamEntity
* @throws IOException
*/
public static void testInputStreamEntity() throws IOException{
InputStream is = null;
//InputStreamEntity嚴格是對內容和長度相匹配的。用法和BasicHttpEntity類似
InputStreamEntity entity = new InputStreamEntity(is, is.available());
}
FileEntity
自我包含式，可以重複的實體。引數傳入檔案和檔案型別。
/**
* 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");
}
EntityTemplete
從ContentProducer介面接受內容的實體。
在ContentProducer的實現類中寫入想要寫入的內容。
/**
* EntityTemplate
* @throws IOException
*/
public static void testEntityTemplate() throws IOException{
ContentProducer producer = new ContentProducer() {
@Override
public void writeTo(OutputStream outstream) throws IOException {
outstream.write("這是什麼東東》。".getBytes());
}
};
EntityTemplate entity = new EntityTemplate(producer);
entity.writeTo(System.out);
}
HttpEntityWrapper
這個是建立被包裝實體的基類，有被包裝實體的引用。
相當於實體的代理類，被包裝實體是他的一個屬性。
下面是這個類的原始碼：
/*
* ====================================================================
* 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();
}
}
BufferedHttpEntity
是HttpEntityWarpper的子類，可以把不可以重複的實體，實現成可以重複的實體。
它從提供的實體中讀取內容，快取到內容中。
原始碼如下：
/*
* ====================================================================
* 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