java檔案流方式下載檔案
阿新 • • 發佈:2018-12-31
該方式Java中基本上都通用,主要4個步驟,下面的ServletContext物件可以不用,可以根據自己的方式來。
這裡我使用的是SpringMVC,不過它在這裡的唯一用途就是用來獲取ServletContext物件,這個物件的用途,下面例項中有說明
需要用到兩個jar包: commons-fileupload.jar 和 commons-io.jar
程式碼如下:
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.context.ServletContextAware;
import javax.servlet.ServletContext;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
@Controller
public class FileController implements ServletContextAware{
//Spring這裡是通過實現ServletContextAware介面來注入ServletContext物件
private ServletContext servletContext;
@Override
public void setServletContext(ServletContext servletContext) {
this.servletContext = servletContext;
}
@RequestMapping("file/download")
public void fileDownload(HttpServletResponse response){
//獲取網站部署路徑(通過ServletContext物件),用於確定下載檔案位置,從而實現下載
String path = servletContext.getRealPath("/");
//1.設定檔案ContentType型別,這樣設定,會自動判斷下載檔案型別
response.setContentType("multipart/form-data");
//2.設定檔案頭:最後一個引數是設定下載檔名(假如我們叫zms.jpg,這裡是設定名稱)
response.setHeader("Content-Disposition", "attachment;fileName="+"zms.jpg");
ServletOutputStream out=null;
FileInputStream inputStream=null;
//通過檔案路徑獲得File物件(假如此路徑中有一個 zms.jpg 檔案)
File file = new File(path + "download/" + "zms.jpg");
try {
inputStream = new FileInputStream(file);
//3.通過response獲取ServletOutputStream物件(out)
out = response.getOutputStream();
int b = 0;
byte[] buffer = new byte[512];
while (b != -1){
b = inputStream.read(buffer);
if(b != -1){
out.write(buffer,0,b);//4.寫到輸出流(out)中
}
}
} catch (IOException e) {
e.printStackTrace();
}finally{
try{
if(inputStream!=null){
inputStream.close();
}
if(out!=null){
out.close();
out.flush();
}
}catch (IOException e) {
e.printStackTrace();
}
}
}
}
第二種方式,直接通過response得到輸出流
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.log4j.Logger;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
@RequestMapping(value="tempDownLoad")
public void tempDownLoad(HttpServletRequest request,HttpServletResponse response){
InputStream in = null;
try{
//1.設定檔案ContentType型別,這樣設定,會自動判斷下載檔案型別
response.setContentType("multipart/form-data");
//2.設定檔案頭:最後一個引數是設定下載檔名
response.setHeader("Content-Disposition", "attachment;fileName=zms.jpg");
//通過檔案路徑獲得File物件(假如此路徑中有一個 zms.jpg 檔案)
File file = new File("E:/template/zms.jpg");
in = new FileInputStream(file);
//3.通過response獲取ServletOutputStream物件(out)
int b = 0;
byte[] buffer = new byte[512];
while (b != -1){
b = in.read(buffer);
if(b != -1){
response.getOutputStream().write(buffer,0,b);//4.寫到輸出流(out)中
}
}
} catch (Exception e) {
}finally{
try {
if (in != null) {
in.close();
}
response.getOutputStream().flush();
} catch (IOException e) {
e.printStackTrace();
logger.error("關閉檔案IOException!");
}
}
}