https协议对于开发者而言其实只是多了一步证书验证的过程。这个证书正常情况下被jdk/jre/security/cacerts所管理。里面证书包含两种情况：
1、机构所颁发的被认证的证书，这种证书的网站在浏览器访问时https头显示为绿色如百度
2、个人所设定的证书，这种证书的网站在浏览器里https头显示为红色×，且需要点击信任该网站才能继续访问。而点击信任这一步的操作就是我们在java代码访问https网站时区别于http请求需要做的事情。
所以JAVA发送Https请求有两种情况，三种解决办法：
第一种情况：Https网站的证书为机构所颁发的被认证的证书，这种情况下和http请求一模一样，无需做任何改变，用HttpsURLConnection或者HttpURLConnection都可以
public static void main(String[] args) throws Exception{
URL serverUrl = new URL("https://xxxx");
HttpURLConnection conn = (HttpURLConnection) serverUrl.openConnection();
conn.setRequestMethod("GET");
conn.setRequestProperty("Content-type", "application/json");
//必须设置false，否则会自动redirect到重定向后的地址
conn.setInstanceFollowRedirects(false);
conn.connect();
String result = getReturn(conn);
}
/*请求url获取返回的内容*/
public static String getReturn(HttpURLConnection connection) throws IOException{
StringBuffer buffer = new StringBuffer();
//将返回的输入流转换成字符串
try(InputStream inputStream = connection.getInputStream();
InputStreamReader inputStreamReader = new InputStreamReader(inputStream, ConstantInfo.CHARSET);
BufferedReader bufferedReader = new BufferedReader(inputStreamReader);){
String str = null;
while ((str = bufferedReader.readLine()) != null) {
buffer.append(str);
}
String result = buffer.toString();
return result;
}
}
第二种情况：个人所设定的证书，这种证书默认不被信任，需要我们自己选择信任，信任的办法有两种：
A、将证书导入java的运行环境中
- 从该网站下载或者从网站开发者出获取证书cacert.crt
- 运行命令将证书导入java运行环境：keytool -import -keystore %JAVA_HOME%\jre\lib\security\cacerts -file cacert.crt -alias xxx
- 完成。java代码中发送https的请求和http一样，同第一种情况。
B、忽略证书验证过程，忽略之后任何Https协议网站皆能正常访问，同第一种情况
-
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;
import javax.net.ssl.X509TrustManager;
public class MyX509TrustManager implements X509TrustManager {
@Override
public void checkClientTrusted(X509Certificate certificates[],String authType) throws CertificateException {
}
@Override
public void checkServerTrusted(X509Certificate[] ax509certificate,String s) throws CertificateException {
}
@Override
public X509Certificate[] getAcceptedIssuers() {
// TODO Auto-generated method stub
return null;
}
} -
public static void main(String[] args) throws Exception{ SSLContext sslcontext = SSLContext.getInstance("SSL","SunJSSE"); sslcontext.init(null, new TrustManager[]{new MyX509TrustManager()}, new java.security.SecureRandom()); URL url = new URL("https://xxxx"); HostnameVerifier ignoreHostnameVerifier = new HostnameVerifier() { public boolean verify(String s, SSLSession sslsession) { System.out.println("WARNING: Hostname is not matched for cert."); return true; } }; HttpsURLConnection.setDefaultHostnameVerifier(ignoreHostnameVerifier); HttpsURLConnection.setDefaultSSLSocketFactory(sslcontext.getSocketFactory()); //之后任何Https协议网站皆能正常访问，同第一种情况}
C、java代码中加载证书，必须使用HttpsURLConnection方式
- 从网站开发者出获取生成证书的密钥库cacert.keystore
import java.io.FileInputStream;
import java.security.KeyStore;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;
import javax.net.ssl.TrustManager;
import javax.net.ssl.TrustManagerFactory;
import javax.net.ssl.X509TrustManager;
public class MyX509TrustManager implements X509TrustManager {
/*
* The default X509TrustManager returned by SunX509. We'll delegate
* decisions to it, and fall back to the logic in this class if the
* default X509TrustManager doesn't trust it.
*/
X509TrustManager sunJSSEX509TrustManager;
MyX509TrustManager() throws Exception {
// create a "default" JSSE X509TrustManager.
KeyStore ks = KeyStore.getInstance("JKS");
ks.load(new FileInputStream("cancert.keystore"),
"changeit".toCharArray());
TrustManagerFactory tmf =
TrustManagerFactory.getInstance("SunX509", "SunJSSE");
tmf.init(ks);
TrustManager tms [] = tmf.getTrustManagers();
/*
* Iterate over the returned trustmanagers, look
* for an instance of X509TrustManager. If found,
* use that as our "default" trust manager.
*/
for (int i = 0; i < tms.length; i++) {
if (tms[i] instanceof X509TrustManager) {
sunJSSEX509TrustManager = (X509TrustManager) tms[i];
return;
}
}
/*
* Find some other way to initialize, or else we have to fail the
* constructor.
*/
throw new Exception("Couldn't initialize");
}
/*
* Delegate to the default trust manager.
*/
public void checkClientTrusted(X509Certificate[] chain, String authType)
throws CertificateException {
try {
sunJSSEX509TrustManager.checkClientTrusted(chain, authType);
} catch (CertificateException excep) {
// do any special handling here, or rethrow exception.
}
}
/*
* Delegate to the default trust manager.
*/
public void checkServerTrusted(X509Certificate[] chain, String authType)
throws CertificateException {
try {
sunJSSEX509TrustManager.checkServerTrusted(chain, authType);
} catch (CertificateException excep) {
/*
* Possibly pop up a dialog box asking whether to trust the
* cert chain.
*/
}
}
/*
* Merely pass this through.
*/
public X509Certificate[] getAcceptedIssuers() {
return sunJSSEX509TrustManager.getAcceptedIssuers();
}
}public static void main(String[] args) throws Exception{ SSLContext sslcontext = SSLContext.getInstance("SSL","SunJSSE"); sslcontext.init(null, new TrustManager[]{new MyX509TrustManager()}, new java.security.SecureRandom()); URL serverUrl = new URL("https://xxxx"); HttpsURLConnection conn = (HttpsURLConnection) serverUrl.openConnection(); conn.setSSLSocketFactory(sslcontext.getSocketFactory()); conn.setRequestMethod("GET"); conn.setRequestProperty("Content-type", "application/json"); //必须设置false，否则会自动redirect到重定向后的地址 conn.setInstanceFollowRedirects(false); conn.connect(); String result = getReturn(conn); } /*请求url获取返回的内容*/ public static String getReturn(HttpsURLConnection connection) throws IOException{ StringBuffer buffer = new StringBuffer(); //将返回的输入流转换成字符串 try(InputStream inputStream = connection.getInputStream(); InputStreamReader inputStreamReader = new InputStreamReader(inputStream, ConstantInfo.CHARSET); BufferedReader bufferedReader = new BufferedReader(inputStreamReader);){ String str = null; while ((str = bufferedReader.readLine()) != null) { buffer.append(str); } String result = buffer.toString(); return result; }}