JavaSE_URLConnection/HttpURLConnection发送HTTP请求的方法（一）

原文地址： https://www.cnblogs.com/h--d/p/5495524.html

 Java原生的API可用于发送HTTP请求


 即java.net.URL、java.net.URLConnection，JDK自带的类；


 
发送请求的流程：


 1.通过统一资源定位器（java.net.URL）获取连接器（java.net.URLConnection）


 2.设置请求的参数


 3.发送请求


 4.以输入流的形式获取返回内容


 5.关闭输入流

package com.util;import java.io.BufferedReader;import java.io.IOException;import java.io.InputStream;import java.io.InputStreamReader;import java.io.OutputStream;import java.io.OutputStreamWriter;import java.net.HttpURLConnection;import java.net.MalformedURLException;import java.net.URL;import java.net.URLConnection;import java.util.Iterator;import java.util.Map;public class HttpConnectionUtil {    // post请求    public static final String HTTP_POST = "POST";    // get请求    public static final String HTTP_GET = "GET";    // utf-8字符编码    public static final String CHARSET_UTF_8 = "utf-8";    // HTTP内容类型。如果未指定ContentType，默认为TEXT/HTML    public static final String CONTENT_TYPE_TEXT_HTML = "text/xml";    // HTTP内容类型。相当于form表单的形式，提交暑假    public static final String CONTENT_TYPE_FORM_URL = "application/x-www-form-urlencoded";    // 请求超时时间    public static final int SEND_REQUEST_TIME_OUT = 50000;    // 将读超时时间    public static final int READ_TIME_OUT = 50000;    /**     *      * @param requestType     *            请求类型     * @param urlStr     *            请求地址     * @param body     *            请求发送内容     * @return 返回内容     */    public static String requestMethod(String requestType, String urlStr, String body) {        // 是否有http正文提交        boolean isDoInput = false;        if (body != null && body.length() > 0)            isDoInput = true;        OutputStream outputStream = null;        OutputStreamWriter outputStreamWriter = null;        InputStream inputStream = null;        InputStreamReader inputStreamReader = null;        BufferedReader reader = null;        StringBuffer resultBuffer = new StringBuffer();        String tempLine = null;        try {            // 统一资源            URL url = new URL(urlStr);            // 连接类的父类，抽象类            URLConnection urlConnection = url.openConnection();            // http的连接类            HttpURLConnection httpURLConnection = (HttpURLConnection) urlConnection;            // 设置是否向httpUrlConnection输出，因为这个是post请求，参数要放在            // http正文内，因此需要设为true, 默认情况下是false;            if (isDoInput) {                httpURLConnection.setDoOutput(true);                httpURLConnection.setRequestProperty("Content-Length", String.valueOf(body.length()));            }            // 设置是否从httpUrlConnection读入，默认情况下是true;            httpURLConnection.setDoInput(true);            // 设置一个指定的超时值（以毫秒为单位）            httpURLConnection.setConnectTimeout(SEND_REQUEST_TIME_OUT);            // 将读超时设置为指定的超时，以毫秒为单位。            httpURLConnection.setReadTimeout(READ_TIME_OUT);            // Post 请求不能使用缓存            httpURLConnection.setUseCaches(false);            // 设置字符编码            httpURLConnection.setRequestProperty("Accept-Charset", CHARSET_UTF_8);            // 设置内容类型            httpURLConnection.setRequestProperty("Content-Type", CONTENT_TYPE_FORM_URL);            // 设定请求的方法，默认是GET            httpURLConnection.setRequestMethod(requestType);            // 打开到此 URL 引用的资源的通信链接（如果尚未建立这样的连接）。            // 如果在已打开连接（此时 connected 字段的值为 true）的情况下调用 connect 方法，则忽略该调用。            httpURLConnection.connect();            if (isDoInput) {                outputStream = httpURLConnection.getOutputStream();                outputStreamWriter = new OutputStreamWriter(outputStream);                outputStreamWriter.write(body);                outputStreamWriter.flush();// 刷新            }            if (httpURLConnection.getResponseCode() >= 300) {                throw new Exception(                        "HTTP Request is not success, Response code is " + httpURLConnection.getResponseCode());            }            if (httpURLConnection.getResponseCode() == HttpURLConnection.HTTP_OK) {                inputStream = httpURLConnection.getInputStream();                inputStreamReader = new InputStreamReader(inputStream);                reader = new BufferedReader(inputStreamReader);                while ((tempLine = reader.readLine()) != null) {                    resultBuffer.append(tempLine);                    resultBuffer.append("\n");                }            }        } catch (MalformedURLException e) {            // TODO Auto-generated catch block            e.printStackTrace();        } catch (IOException e) {            // TODO Auto-generated catch block            e.printStackTrace();        } catch (Exception e) {            // TODO Auto-generated catch block            e.printStackTrace();        } finally {// 关闭流            try {                if (outputStreamWriter != null) {                    outputStreamWriter.close();                }            } catch (Exception e) {                // TODO Auto-generated catch block                e.printStackTrace();            }            try {                if (outputStream != null) {                    outputStream.close();                }            } catch (Exception e) {                // TODO Auto-generated catch block                e.printStackTrace();            }            try {                if (reader != null) {                    reader.close();                }            } catch (Exception e) {                // TODO Auto-generated catch block                e.printStackTrace();            }            try {                if (inputStreamReader != null) {                    inputStreamReader.close();                }            } catch (Exception e) {                // TODO Auto-generated catch block                e.printStackTrace();            }            try {                if (inputStream != null) {                    inputStream.close();                }            } catch (Exception e) {                // TODO Auto-generated catch block                e.printStackTrace();            }        }        return resultBuffer.toString();    }    /**     * 将map集合的键值对转化成：key1=value1&key2=value2 的形式     *      * @param parameterMap     *            需要转化的键值对集合     * @return 字符串     */    public static String convertStringParamter(Map parameterMap) {        StringBuffer parameterBuffer = new StringBuffer();        if (parameterMap != null) {            Iterator iterator = parameterMap.keySet().iterator();            String key = null;            String value = null;            while (iterator.hasNext()) {                key = (String) iterator.next();                if (parameterMap.get(key) != null) {                    value = (String) parameterMap.get(key);                } else {                    value = "";                }                parameterBuffer.append(key).append("=").append(value);                if (iterator.hasNext()) {                    parameterBuffer.append("&");                }            }        }        return parameterBuffer.toString();    }    public static void main(String[] args) throws MalformedURLException {        System.out.println(requestMethod(HTTP_GET, "http://127.0.0.1:8080/test/TestHttpRequestServlet",                "username=123&password=我是谁"));    }}