如果您有java.io.InputStream对象，应如何处理该对象并产生String ？
假设我有一个包含文本数据的InputStream ，并且我想将其转换为String ，那么例如，我可以将其写入日志文件。
接受InputStream并将其转换为String的最简单方法是什么？
public String convertStreamToString(InputStream is) {
// ???
}
#1楼
这是最好的纯Java解决方案，非常适合Android和任何其他JVM。
该解决方案的效果非常好……它简单，快速，并且在相同大小的流上都可以使用！ （请参阅上面的基准。 第8号 ）
public String readFullyAsString(InputStream inputStream, String encoding)
throws IOException {
return readFully(inputStream).toString(encoding);
}
public byte[] readFullyAsBytes(InputStream inputStream)
throws IOException {
return readFully(inputStream).toByteArray();
}
private ByteArrayOutputStream readFully(InputStream inputStream)
throws IOException {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
int length = 0;
while ((length = inputStream.read(buffer)) != -1) {
baos.write(buffer, 0, length);
}
return baos;
}
#2楼
这是使用字节数组缓冲区仅使用JDK的方法。 实际上，这就是commons-io IOUtils.copy()方法的全部工作方式。 如果要从Reader而不是InputStream复制，则可以用char[]替换byte[] 。
import java.io.ByteArrayOutputStream;
import java.io.InputStream;
...
InputStream is = ....
ByteArrayOutputStream baos = new ByteArrayOutputStream(8192);
byte[] buffer = new byte[8192];
int count = 0;
try {
while ((count = is.read(buffer)) != -1) {
baos.write(buffer, 0, count);
}
}
finally {
try {
is.close();
}
catch (Exception ignore) {
}
}
String charset = "UTF-8";
String inputStreamAsString = baos.toString(charset);
#3楼
如果使用流阅读器，请确保最后关闭流
private String readStream(InputStream iStream) throws IOException {
//build a Stream Reader, it can read char by char
InputStreamReader iStreamReader = new InputStreamReader(iStream);
//build a buffered Reader, so that i can read whole line at once
BufferedReader bReader = new BufferedReader(iStreamReader);
String line = null;
StringBuilder builder = new StringBuilder();
while((line = bReader.readLine()) != null) { //Read till end
builder.append(line);
builder.append("\n"); // append new line to preserve lines
}
bReader.close(); //close all opened stuff
iStreamReader.close();
//iStream.close(); //EDIT: Let the creator of the stream close it!
// some readers may auto close the inner stream
return builder.toString();
}
编辑：在JDK 7+上，您可以使用try-with-resources构造。
/**
* Reads the stream into a string
* @param iStream the input stream
* @return the string read from the stream
* @throws IOException when an IO error occurs
*/
private String readStream(InputStream iStream) throws IOException {
//Buffered reader allows us to read line by line
try (BufferedReader bReader =
new BufferedReader(new InputStreamReader(iStream))){
StringBuilder builder = new StringBuilder();
String line;
while((line = bReader.readLine()) != null) { //Read till end
builder.append(line);
builder.append("\n"); // append new line to preserve lines
}
return builder.toString();
}
}
#4楼
经过一些实验，这是我想到的最优雅的纯Java（无库）解决方案：
public static String fromStream(InputStream in) throws IOException
{
BufferedReader reader = new BufferedReader(new InputStreamReader(in));
StringBuilder out = new StringBuilder();
String newLine = System.getProperty("line.separator");
String line;
while ((line = reader.readLine()) != null) {
out.append(line);
out.append(newLine);
}
return out.toString();
}
#5楼
这是无需使用任何第三方库即可将InputStream转换为String的完整方法。 将StringBuilder用于单线程环境，否则使用StringBuffer 。
public static String getString( InputStream is) throws IOException {
int ch;
StringBuilder sb = new StringBuilder();
while((ch = is.read()) != -1)
sb.append((char)ch);
return sb.toString();
}