如果您有java.io.InputStream对象,应该如何处理该对象并生成String?
假设我有一个包含文本数据的InputStream,我想将其转换为String,例如,我可以将其写入日志文件。
获取InputStream并将其转换为字符串的最简单方法是什么?
public String convertStreamToString(InputStream is) {
// ???
}
如果您有java.io.InputStream对象,应该如何处理该对象并生成String?
假设我有一个包含文本数据的InputStream,我想将其转换为String,例如,我可以将其写入日志文件。
获取InputStream并将其转换为字符串的最简单方法是什么?
public String convertStreamToString(InputStream is) {
// ???
}
当前回答
考虑到文件,首先应该获得java.io.Reader实例。然后可以将其读取并添加到StringBuilder中(如果我们不在多个线程中访问StringBuffer,我们就不需要StringBuffer了,StringBuilder速度更快)。这里的技巧是我们在块中工作,因此不需要其他缓冲流。块大小被参数化以用于运行时性能优化。
public static String slurp(final InputStream is, final int bufferSize) {
final char[] buffer = new char[bufferSize];
final StringBuilder out = new StringBuilder();
try (Reader in = new InputStreamReader(is, "UTF-8")) {
for (;;) {
int rsz = in.read(buffer, 0, buffer.length);
if (rsz < 0)
break;
out.append(buffer, 0, rsz);
}
}
catch (UnsupportedEncodingException ex) {
/* ... */
}
catch (IOException ex) {
/* ... */
}
return out.toString();
}
其他回答
此代码适用于新的Java学习者:
private String textDataFromFile;
public String getFromFile(InputStream myInputStream) throws FileNotFoundException, IOException {
BufferedReader bufferReader = new BufferedReader(new InputStreamReader(myInputStream));
StringBuilder stringBuilder = new StringBuilder();
String eachStringLine;
while ((eachStringLine = bufferReader.readLine()) != null) {
stringBuilder.append(eachStringLine).append("\n");
}
textDataFromFile = stringBuilder.toString();
return textDataFromFile;
}
下面是如何仅使用JDK使用字节数组缓冲区来实现这一点。这实际上就是commons-ioIOUItils.copy()方法的工作原理。如果要从Reader而不是InputStream复制,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);
Use:
InputStream in = /* Your InputStream */;
StringBuilder sb = new StringBuilder();
BufferedReader br = new BufferedReader(new InputStreamReader(in));
String read;
while ((read=br.readLine()) != null) {
//System.out.println(read);
sb.append(read);
}
br.close();
return sb.toString();
将inputStream转换为字符串的方法
public static String getStringFromInputStream(InputStream inputStream) {
BufferedReader bufferedReader = null;
StringBuilder stringBuilder = new StringBuilder();
String line;
try {
bufferedReader = new BufferedReader(new InputStreamReader(
inputStream));
while ((line = bufferedReader.readLine()) != null) {
stringBuilder.append(line);
}
} catch (IOException e) {
logger.error(e.getMessage());
} finally {
if (bufferedReader != null) {
try {
bufferedReader.close();
} catch (IOException e) {
logger.error(e.getMessage());
}
}
}
return stringBuilder.toString();
}
当输入流来自类路径资源(这似乎是一项流行任务)时,Guava提供了更短的高效自动关闭解决方案:
byte[] bytes = Resources.toByteArray(classLoader.getResource(path));
or
String text = Resources.toString(classLoader.getResource(path), StandardCharsets.UTF_8);
还有ByteSource和CharSource的一般概念,它们温和地负责打开和关闭流。
因此,例如,不要显式打开一个小文件来读取其内容:
String content = Files.asCharSource(new File("robots.txt"), StandardCharsets.UTF_8).read();
byte[] data = Files.asByteSource(new File("favicon.ico")).read();
或者只是
String content = Files.toString(new File("robots.txt"), StandardCharsets.UTF_8);
byte[] data = Files.toByteArray(new File("favicon.ico"));