前几天写了个多线程通过HTTP下载文件的小程序，其中简单写了个HttpClient. 源码：GitHub
1 定义一个抽象BaseHttpMethod类
<pre>
`
public abstract class BaseHttpMethod {
protected static String HEAD = "HEAD";
protected static String GET = "GET";
protected static String POST = "POST";
String url;
protected Map paras = new HashMap();
protected abstract String getMethod();
protected abstract BaseBuilder getBuilder();
protected Map getParamters(){
return paras;
}
public void putParamter(String key,Object value){
paras.put(key, value);
}
protected void setUrl(String url) {
this.url = url;
}
protected String getUrl(){
return url;
}
protected BaseHttpMethod() {
}
protected BaseHttpMethod(String url) {
this.url = url;
}
}
`
</pre>
下面定义了3个实现类：HttpGet，HttpPost，HttpHead
<pre>
`
public class HttpPost extends BaseHttpMethod {
@Override
public String getMethod() {
return POST;
}
public HttpPost() {
}
public HttpPost(String url) {
super(url);
}
@Override
protected BaseBuilder getBuilder() {
return new PostConnectBuilder(this);
}
}
`
</pre>
其他2个HttpGet，HttpHead和这个差不多
2 定义一个Response 接口IHttpResponse
<pre>
`
public interface IHttpResponse {
public int getStatusCode() throws IOException;
public InputStream getInputStream() throws IOException;
public String getContent();
public Map<String, List<String>> getHeaders();
public String getHeader(String name);
public void close();
}
`
</pre>
HttpResponse简单实现了这个接口
<pre>
`
public class HttpResponse implements IHttpResponse {
private InputStream inputStream;
private HttpURLConnection con;
public HttpResponse(HttpURLConnection con) {
this.con = con;
}
@Override
public int getStatusCode() throws IOException {
return con != null ? con.getResponseCode() : -1;
}
@Override
public InputStream getInputStream() throws IOException {
inputStream = null != con ? con.getInputStream() : null;
return inputStream;
}
@Override
public String getContent() {
if (inputStream != null) {
StringBuffer content = new StringBuffer();
BufferedInputStream bufferInputStream = new BufferedInputStream(
inputStream);
byte[] data = new byte[1024];
int length;
try {
while ((length = bufferInputStream.read(data)) > 0) {
content.append(new String(data, 0, length));
}
return content.toString();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
return null;
}
@Override
public Map<String, List<String>> getHeaders() {
return null != con ? con.getHeaderFields() : null;
}
@Override
public String getHeader(String name) {
return null != con ? con.getHeaderField(name) : null;
}
@Override
public void close() {
if (null != null)
con.disconnect();
}
}
`
</pre>
3 简单定义一个HttpClient
<pre>
`
public class HttpClient {
public static String HEAD = "HEAD";
public static String GET = "GET";
public static String POST = "POST";
private static HttpClient instance;
private HttpClient (){
}
public static HttpClient getInstance(){
if(null == instance){
synchronized (HttpClient .class) {
instance =new HttpClient ();
}
}
return instance;
}
public IHttpResponse exec(BaseHttpMethod method) throws IOException{
return exec(method,null);
}
public IHttpResponse exec(BaseHttpMethod method,Map property) throws IOException{
HttpURLConnection con = ConnectFactory.getInstance().getCon(method,property);
return new HttpResponse(con);
}
}
`
</pre>
这里用到一个ConnectFactory 来获得URLHttpConnection
4 一个简单ConnectFactory
<pre>
`
public class ConnectFactory {
private static int CON_TIME_OUT = 5 * 100;
private static int READ_TIME_OUT = 10 * 1000;
public void setConnectTimeout(int connectTimeout) {
CON_TIME_OUT = connectTimeout;
}
public void setReadTimeout(int readTimeout) {
READ_TIME_OUT = readTimeout;
}
private static ConnectFactory instance;
private ConnectFactory() {
}
public static ConnectFactory getInstance() {
if (null == instance) {
synchronized (ConnectFactory.class) {
instance = new ConnectFactory();
}
}
return instance;
}
public HttpURLConnection getCon(BaseHttpMethod method,Map<String,String> property) throws IOException {
HttpURLConnection con = method.getBuilder().build();
con.setConnectTimeout(CON_TIME_OUT);
con.setReadTimeout(READ_TIME_OUT);
if(null != property && property.size()>0){
Iterator keyIt = property.keySet().iterator();
while(keyIt.hasNext()){
String key = (String) keyIt.next();
String value = property.get(key);
con.setRequestProperty(key,value);
}
}
//some sites will refuse, if no "User-Agent", so set default value
if(property==null || !property.containsKey("User-Agent")){
con.setRequestProperty("User-Agent", "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Firefox/38.0");
}
con.connect();
method.getBuilder().doOutPut(con);
return con;
}
public HttpURLConnection getCon(BaseHttpMethod method) throws IOException {
return getCon(method, null);
}
}
</pre> 在这个工厂方法中用到了一个Builder, 其中的抽象类为： <pre>
public abstract class BaseBuilder {
protected BaseHttpMethod method;
public BaseBuilder(BaseHttpMethod method) {
this.method=method;
}
protected void doOutPut(HttpURLConnection con){
}
protected abstract HttpURLConnection build() throws IOException;
protected String buildParamters(){
Map paras = method.getParamters();
StringBuffer sb = new StringBuffer();
if(paras!=null && paras.size()>0){
Iterator<String> keyIt = paras.keySet().iterator();
while(keyIt.hasNext()){
String key = keyIt.next();
String value = (String) paras.get(key);
String encodedValue = null;
try {
encodedValue = URLEncoder.encode(value, "UTF-8");
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
if(encodedValue!=null){
sb.append(key).append("=").append(encodedValue);
}else{
sb.append(key).append("=").append(value);
}
if(keyIt.hasNext())sb.append("&");
}
}
return sb.toString();
}
}
</pre> 其中的HeadConnectBuilder <pre>
public class HeadConnectBuilder extends BaseBuilder {
public HeadConnectBuilder(BaseHttpMethod method) {
super(method);
}
@Override
protected HttpURLConnection build() throws IOException {
String surl = method.getUrl();
URL url = new URL(surl);
HttpURLConnection con = (HttpURLConnection) url.openConnection();
con.setRequestMethod(method.getMethod());
return con;
}
}
`
</pre>
5 简单实用
<pre>
<code>
public static void main(String[] args) {
BaseHttpMethod get = new HttpGet("http://www.jianshu.com");
DownLoadHttpClient client = DownLoadHttpClient.getInstance();
try {
IHttpResponse response = client.exec(get);
System.out.println(response.getContent());
} catch (IOException e) {
e.printStackTrace();
}
}
</code>
</pre>
输出：
<!DOCTYPE html>
<html>
<head>
。。。。。。。
</html>
