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Spring MVC - StreamingResponseBody Examples

Spring MVC 

StreamingResponseBody is used for asynchronous request processing where the application can write directly to the response OutputStream. 

package com.logicbig.example;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.mvc.method.annotation.StreamingResponseBody;

import java.io.IOException;
import java.io.OutputStream;

@Controller
public class TestController {

    @RequestMapping("/")
    public StreamingResponseBody handleRequest () {

        return new StreamingResponseBody() {
            @Override
            public void writeTo (OutputStream out) throws IOException {
                for (int i = 0; i < 1000; i++) {
                    out.write((Integer.toString(i) + " - ")
                                        .getBytes());
                    out.flush();
                    try {
                        Thread.sleep(5);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        };
    }
}
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StreamingResponseBody can be used with ResponseEntity: 

package com.logicbig.example;

import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.mvc.method.annotation.StreamingResponseBody;

import java.io.IOException;
import java.io.OutputStream;

@Controller
public class TestController2 {

    @RequestMapping("/test")
    public ResponseEntity<StreamingResponseBody> handleRequest () {

        StreamingResponseBody responseBody = new StreamingResponseBody() {
            @Override
            public void writeTo (OutputStream out) throws IOException {
                for (int i = 0; i < 1000; i++) {
                    out.write((Integer.toString(i) + " - ")
                                        .getBytes());
                    out.flush();
                    try {
                        Thread.sleep(5);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }

                }
            }
        };

        return new ResponseEntity(responseBody, HttpStatus.OK);
    }
}
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package com.logicbig.example;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.servlet.mvc.method.annotation.StreamingResponseBody;

import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
import java.io.OutputStream;
import java.util.concurrent.Callable;

@Controller
public class MyWebController2 {

    @RequestMapping("/test")
    public StreamingResponseBody handleRequest (HttpServletRequest r) {
        System.out.println("asyncSupported: "+ r.isAsyncSupported());
        System.out.println(Thread.currentThread().getName());

        return new StreamingResponseBody() {
            @Override
            public void writeTo (OutputStream outputStream) throws IOException {
                System.out.println(Thread.currentThread().getName());
                outputStream.write("from test request".getBytes());
            }
        };
    }
}
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package com.logicbig.example;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.mvc.method.annotation.StreamingResponseBody;
import java.io.ObjectOutputStream;
import java.math.BigInteger;
import java.util.HashMap;
import java.util.Map;

@Controller
public class MyController {

    @RequestMapping("/")
    public StreamingResponseBody handleRequest () {
        return outputStream -> {
            Map<String, BigInteger> map = new HashMap<>();
            map.put("one", BigInteger.ONE);
            map.put("ten", BigInteger.TEN);
            try(ObjectOutputStream oos = new ObjectOutputStream(outputStream)){
                oos.writeObject(map);
            }
        };
    }
}
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See Also