import javax.servlet.http.HttpServletRequest; 
import javax.servlet.ServletInputStream; 
import java.util.Dictionary; 
import java.util.Hashtable; 
import java.io.*;
public class FileUpload { 
// 定義變量，用來存儲上傳文件的名字，路徑等
private String savePath, filepath, filename, contentType; 
// 保存了用戶在表單中輸入數據的名字/值對
private Dictionary fields; 

// 獲得文件名字
public String getFilename() { 
return filename; 
} 
// 獲得上傳文件的路徑
public String getFilepath() { 
return filepath; 
} 
// 設定上傳文件的路徑，如果沒有設定就保存在服務器默認目錄
public void setSavePath(String savePath) { 
this.savePath = savePath; 
} 
// 得到文件類型
public String getContentType() { 
return contentType; 
} 

public String getFieldValue(String fieldName) { 
if (fields == null || fieldName == null) 
return null; 
return (String) fields.get(fieldName); 
} 

private void setFilename(String s) { 
if (s==null) 
return; 
int pos = s.indexOf("filename=\""); 
if (pos != -1) { 
filepath = s.substring(pos+10, s.length()-1); 
pos = filepath.lastIndexOf("\\"); 
if (pos != -1) 
filename = filepath.substring(pos + 1); 
else 
filename = filepath; 
} 
} 

private void setContentType(String s) { 
if (s==null) 
return; 
int pos = s.indexOf(": "); 
if (pos != -1) 
contentType = s.substring(pos+2, s.length()); 
} 

public void doUpload(HttpServletRequest request) throws IOException { 
ServletInputStream in = request.getInputStream(); 
byte[] line = new byte[128]; 
int i = in.readLine(line, 0, 128); 
if (i < 3) 
return; 
int boundaryLength = i - 2; 
String boundary = new String(line, 0, boundaryLength); //-2丟棄換行字符 
fields = new Hashtable(); 

while (i != -1) { 
String newLine = new String(line, 0, i); 
if (newLine.startsWith("Content-Disposition: form-data; name=\"")) { 
if (newLine.indexOf("filename=\"") != -1) { 
setFilename(new String(line, 0, i-2)); 
if (filename==null) 
return; 

//文件內容 
i = in.readLine(line, 0, 128); 
setContentType(new String(line, 0, i-2)); 
i = in.readLine(line, 0, 128); 

//空行 
i = in.readLine(line, 0, 128); 
newLine = new String(line, 0, i); 
PrintWriter pw = new PrintWriter(new BufferedWriter(new 
FileWriter((savePath==null? "" : savePath) + filename))); 
while (i != -1 && !newLine.startsWith(boundary)) { 
// 文件內容的最后一行包含換行字符 

// 因此我們必須檢查當前行是否是最 

// 后一行 
i = in.readLine(line, 0, 128); 
if ((i==boundaryLength+2 || i==boundaryLength+4) 
&& (new String(line, 0, i).startsWith(boundary))) 
pw.print(newLine.substring(0, newLine.length()-2)); 
else 
pw.print(newLine); 
newLine = new String(line, 0, i); 
} 
pw.close(); 
} 
else { 
// 普通表單輸入元素 
// 獲取輸入元素名字 
int pos = newLine.indexOf("name=\""); 
String fieldName = newLine.substring(pos+6, newLine.length()-3); 
i = in.readLine(line, 0, 128); 
i = in.readLine(line, 0, 128); 
newLine = new String(line, 0, i); 
StringBuffer fieldValue = new StringBuffer(128); 
while (i != -1 && !newLine.startsWith(boundary)) { 
// 最后一行包含換行字符 
// 因此我們必須檢查當前行是否是最后一行 
i = in.readLine(line, 0, 128); 
if ((i==boundaryLength+2 || i==boundaryLength+4) 
&& (new String(line, 0, i).startsWith(boundary))) 
fieldValue.append(newLine.substring(0, newLine.length()-2)); 
else 
fieldValue.append(newLine); 
newLine = new String(line, 0, i); 
} 
fields.put(fieldName, fieldValue.toString()); 
} 
} 
i = in.readLine(line, 0, 128); 
} 
} 
}