一、简述：
两要素：①发送http请求的地址（URL）；
②发送http请求的参数（String类型、json字符串类型、xml类型、Map类型）；
二、代码如下：
public class MainTest {
/**
* 向指定URL发送GET方法的请求
*
* @param url
* 发送请求的URL
* @param param
* 请求参数，请求参数应该是 name1=value1&name2=value2 的形式。
* @return URL 所代表远程资源的响应结果
*/
public static String sendGet(String url, String param) {
String result = "";
BufferedReader in = null;
try {
String urlNameString = url + "?" + param;
URL realUrl = new URL(urlNameString);
// 打开和URL之间的连接
URLConnection connection = realUrl.openConnection();
// 设置通用的请求属性
connection.setRequestProperty("accept", "*/*");
connection.setRequestProperty("connection", "Keep-Alive");
connection.setRequestProperty("user-agent",
"Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
// 建立实际的连接
connection.connect();
// 获取所有响应头字段
Map<String, List<String>> map = connection.getHeaderFields();
// 遍历所有的响应头字段
for (String key : map.keySet()) {
System.out.println(key + "--->" + map.get(key));
}
// 定义 BufferedReader输入流来读取URL的响应
in = new BufferedReader(new InputStreamReader(
connection.getInputStream()));
String line;
while ((line = in.readLine()) != null) {
result += line;
}
} catch (Exception e) {
System.out.println("发送GET请求出现异常！" + e);
e.printStackTrace();
}
// 使用finally块来关闭输入流
finally {
try {
if (in != null) {
in.close();
}
} catch (Exception e2) {
e2.printStackTrace();
}
}
return result;
}
/**
* 向指定 URL 发送POST方法的请求
*
* @param url
* 发送请求的 URL
* @param param （String类型）
* 请求参数，请求参数应该是 name1=value1&name2=value2 的形式。
* @return 所代表远程资源的响应结果
*/
public static String sendPost(String url, String param) {
PrintWriter out = null;
BufferedReader in = null;
String result = "";
try {
URL realUrl = new URL(url);
// 打开和URL之间的连接
URLConnection conn = realUrl.openConnection();
// 设置通用的请求属性
conn.setRequestProperty("accept", "*/*");
conn.setRequestProperty("connection", "Keep-Alive");
conn.setRequestProperty("user-agent",
"Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
// 发送POST请求必须设置如下两行
conn.setDoOutput(true);
conn.setDoInput(true);
// 获取URLConnection对象对应的输出流
out = new PrintWriter(conn.getOutputStream());
// 发送请求参数
out.print(param);
// flush输出流的缓冲
out.flush();
// 定义BufferedReader输入流来读取URL的响应
in = new BufferedReader(
new InputStreamReader(conn.getInputStream(),"UTF-8"));
String line;
while ((line = in.readLine()) != null) {
result += line;
}
} catch (Exception e) {
System.out.println("发送 POST 请求出现异常！"+e);
e.printStackTrace();
}
//使用finally块来关闭输出流、输入流
finally{
try{
if(out!=null){
out.close();
}
if(in!=null){
in.close();
}
}
catch(IOException ex){
ex.printStackTrace();
}
}
return result;
}
/**
* 发送post请求
* @param url 路径
* @param jsonObject 参数(json类型)
* @param encoding 编码格式
* @return
* @throws ParseException
* @throws IOException
*/
public static String send(String url, String jsonObject,String encoding) throws ParseException, IOException{
String body = "";
//创建httpclient对象
CloseableHttpClient client = HttpClients.createDefault();
//创建post方式请求对象
HttpPost httpPost = new HttpPost(url);
//装填参数
StringEntity s = new StringEntity(jsonObject.toString(), "utf-8");
s.setContentEncoding(new BasicHeader(HTTP.CONTENT_TYPE,
"application/json"));
//设置参数到请求对象中
httpPost.setEntity(s);
System.out.println("请求地址："+url);
// System.out.println("请求参数："+nvps.toString());
//设置header信息
//指定报文头【Content-type】、【User-Agent】
// httpPost.setHeader("Content-type", "application/x-www-form-urlencoded");
httpPost.setHeader("Content-type", "application/json");
httpPost.setHeader("User-Agent", "Mozilla/4.0 (compatible; MSIE 5.0; Windows NT; DigExt)");
//执行请求操作，并拿到结果（同步阻塞）
CloseableHttpResponse response = client.execute(httpPost);
//获取结果实体
HttpEntity entity = response.getEntity();
if (entity != null) {
//按指定编码转换结果实体为String类型
body = EntityUtils.toString(entity, encoding);
}
EntityUtils.consume(entity);
//释放链接
response.close();
return body;
}
/**
* 发送xml格式的HTTP POST请求
* @param url 请求地址
* @param xml 请求的xml数据
* @return 服务端返回的数据字符串
*/
public static String doPostXml(String url, String xml) {
// 创建Httpclient对象
CloseableHttpClient httpClient = HttpClients.createDefault();
CloseableHttpResponse response = null;
String resultString = "";
try {
// 创建Http Post请求
HttpPost httpPost = new HttpPost(url);
// 创建请求内容
StringEntity entity = new StringEntity(xml, ContentType.APPLICATION_XML);
httpPost.setEntity(entity);
// 执行http请求
response = httpClient.execute(httpPost);
resultString = EntityUtils.toString(response.getEntity(), "utf-8");
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
response.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return resultString;
}
/**
* 发送xml格式的HTTP POST请求
* @param url 请求地址
* @param map 请求的map数据
* @return 服务端返回的数据字符串
*/
public static String doPost(String url, Map<String, Object> param) {
// 创建Httpclient对象
CloseableHttpClient httpClient = HttpClients.createDefault();
CloseableHttpResponse response = null;
String resultString = "";
try {
// 创建Http Post请求
HttpPost httpPost = new HttpPost(url);
// 创建参数列表
if (param != null) {
List<NameValuePair> paramList = new ArrayList<NameValuePair>();
for (String key : param.keySet()) {
Object value = param.get(key);
if(value!=null){
paramList.add(new BasicNameValuePair(key,value+""));
}
}
// 模拟表单
UrlEncodedFormEntity entity = new UrlEncodedFormEntity(paramList,"UTF-8");
httpPost.setEntity(entity);
}
// 执行http请求
response = httpClient.execute(httpPost);
resultString = EntityUtils.toString(response.getEntity(), "utf-8");
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
response.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
System.out.println(resultString);
return resultString;
}
｝
三、jar包补充：
提取码：uedc
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