JAVA调用SAP ODATA服务

1、(401) 未经授权；

       解决方法：将用户名密码加密后，添加到HTTP HEADER中。

String auth = "ZRFC" + ":"  + "Init1234";

        String encodeAuth = "Basic " + new String(Base64.getEncoder().encode(auth.getBytes(StandardCharsets.UTF_8)));

        connection.setRequestProperty("Authorization", encodeAuth);

2、POST方法地址；

    解决方法：要先用GET方法从去调用ODATA中GET_ENTIY方法，例如：http://vhcals4h.com:44301/sap/opu/odata/sap/ztest_srv/HEADERSet('5000000001')，然后再将返回内容作为表身，传到ENTITYSET地址，如：http://vhcals4h.com:44301/sap/opu/odata/sap/ztest_srv/HEADERSet('5000000001')。

3、CSRF跨域问题；

    解决方法：先用GET方法取到TOKEN再放到POST HEADER中。

String csrfToken = connection.getHeaderField("X-CSRF-Token");

connPost.setRequestProperty("X-CSRF-Token", csrfToken);

package odata_test;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileOutputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.StringReader;
import java.io.StringWriter;
import java.net.CookieHandler;
import java.net.CookieManager;
import java.net.CookiePolicy;
import java.net.HttpURLConnection;
import java.net.URL;
import java.nio.charset.StandardCharsets;
import java.util.Base64;
import java.util.List;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;

public class RestfulAction {
    /**
     * @param args
     * @throws Exception
     */
    public static void main(String[] args) throws Exception {
    	//添加cookie支持
    	CookieManager manager = new CookieManager();
    	//设置cookie策略，只接受与你对话服务器的cookie，而不接收Internet上其它服务器发送的cookie
        manager.setCookiePolicy(CookiePolicy.ACCEPT_ORIGINAL_SERVER);
        CookieHandler.setDefault(manager);
        System.out.println(manager.getCookieStore());
        
        String url = "http://vhcals4h.com:44301/sap/opu/odata/sap/ztest_srv/HEADERSet('5000000001')";
        URL serverUrl = new URL(url);
        HttpURLConnection connection = (HttpURLConnection) serverUrl.openConnection();
        connection.setRequestMethod("GET");
        //connection.setRequestProperty("Authorization", "Basic cmF5bW9uZDpJbml0MTIzNA==");
        String auth = "ZRFC" + ":"  + "Init1234";
        String encodeAuth = "Basic " + new String(Base64.getEncoder().encode(auth.getBytes(StandardCharsets.UTF_8)));
        connection.setRequestProperty("Authorization", encodeAuth);
        connection.setRequestProperty("X-CSRF-Token", "Fetch");
        if (connection.getResponseCode() != 200) {
            throw new RuntimeException(
                    "HTTP GET Request Failed with Error code : "
                            + connection.getResponseCode());
        }
//        BufferedReader responseBuffer = new BufferedReader(
//                new InputStreamReader((connection.getInputStream())));
//        String output;
//        System.out.println("Output from Server:  \n");
//        while ((output = responseBuffer.readLine()) != null) {
//            System.out.println(output);			
//        }
        
        //解析XML
        DocumentBuilderFactory bbf = DocumentBuilderFactory.newInstance();
        DocumentBuilder builder = bbf.newDocumentBuilder();
        Document doc = builder.parse(connection.getInputStream());
        //Document doc = builder.parse("src/test.xml");
		Element root = doc.getDocumentElement();
		NodeList nodes = root.getChildNodes();
		if (nodes != null) {
			for ( int i = 0; i < nodes.getLength(); i++ ) {
				Node node = nodes.item(i);
				 // TEXT_NODE 说明该节点是文本节点
                // ELEMENT_NODE 说明该节点是个元素节点
                if (node.getNodeType() == Node.ELEMENT_NODE) {
                    // （7）取得节点的属性值
                    // String email = user.getAttributes()
                    // .getNamedItem("email").getNodeValue();
                    // System.out.println(email);
                    // 注意，节点的属性也是它的子节点。它的节点类型也是Node.ELEMENT_NODE
                    // （8）轮循子节点
                	for (Node subnode = node.getFirstChild(); subnode != null; subnode = subnode.getNextSibling()) {
                		if (subnode.getNodeType() == Node.ELEMENT_NODE) {
                		}
//            			System.out.println("nodeName:" + subnode.getNodeType());
//            			System.out.println("nodeName:" + subnode.getNodeName());
//            			System.out.println("nodeVaule:" + subnode.getNodeValue());
                	}
                	
                }
			}
		}
//		for( int i = 0; i < nodes.getLength(); i++ ) {
//			Node node = nodes.item(i);
//			System.out.println(node.getNodeValue());
//		}
        NodeList belnr = root.getElementsByTagName("d:BELNR");
        belnr.item(0).getFirstChild().setNodeValue("510000");
        System.out.println(belnr.item(0).getFirstChild().getNodeValue());
        
        System.out.println(doc.toString());
      //保存xml文件
        TransformerFactory transformerFactory=TransformerFactory.newInstance();
        Transformer transformer=transformerFactory.newTransformer();
        DOMSource domSource=new DOMSource(doc);
        //设置编码类型
        transformer.setOutputProperty(OutputKeys.ENCODING, "UTF-8");
        //转换成xml文件
        StreamResult result=new StreamResult(new FileOutputStream("src/new.xml"));
        //StreamResult result=new StreamResult();
        transformer.transform(domSource, result);
        //转换成字符串
        StringWriter strWriter = new StringWriter();
        StreamResult resultStr = new StreamResult(strWriter);
        transformer.transform(domSource, resultStr);
        String requestBody = strWriter.getBuffer().toString();
        System.out.println(requestBody);
        //String cookie = connection.getHeaderField("Cookie");
        String csrfToken = connection.getHeaderField("X-CSRF-Token");
        System.out.println(manager.getCookieStore());
        connection.disconnect();
        
        //POST方法
        HttpURLConnection connPost = (HttpURLConnection) new URL("http://vhcals4h.com:44301/sap/opu/odata/sap/ztest_srv/HEADERSet").openConnection();
        connPost.setRequestMethod("POST");
        connPost.setRequestProperty("Authorization", encodeAuth);
        connPost.setRequestProperty("X-CSRF-Token", csrfToken);
        connPost.setRequestProperty("Content-Type", "application/xml");
        //connPost.setRequestProperty("Cookie", cookie);
        connPost.setDoOutput(true);
        connPost.setDoInput(true);
        connPost.setUseCaches(false);
        connPost.setRequestProperty("Connection","Keep-Alive");
        OutputStream outStream = connPost.getOutputStream();
        outStream.write(requestBody.getBytes());
        outStream.flush();
        outStream.close();
        System.out.println(connPost.getResponseCode());
        
        
        connPost.disconnect();
    }
}

　　

4、403错误；

    解决方法：添加Cookie支持。

//添加cookie支持

    CookieManager manager = new CookieManager();

    //设置cookie策略，只接受与你对话服务器的cookie，而不接收Internet上其它服务器发送的cookie

        manager.setCookiePolicy(CookiePolicy.ACCEPT_ORIGINAL_SERVER);

        CookieHandler.setDefault(manager);

        System.out.println(manager.getCookieStore());

另外还涉及到一些XML解析，以下为完整代码，包含GET和POST方法：