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
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"));
其他回答
这里或多或少有sampath的答案,清理了一点并表示为函数:
String streamToString(InputStream in) throws IOException {
StringBuilder out = new StringBuilder();
BufferedReader br = new BufferedReader(new InputStreamReader(in));
for(String line = br.readLine(); line != null; line = br.readLine())
out.append(line);
br.close();
return out.toString();
}
这是一个改编自org.apache.commons.io.IOUtils源代码的答案,适用于那些想要apache实现但不想要整个库的人。
private static final int BUFFER_SIZE = 4 * 1024;
public static String inputStreamToString(InputStream inputStream, String charsetName)
throws IOException {
StringBuilder builder = new StringBuilder();
InputStreamReader reader = new InputStreamReader(inputStream, charsetName);
char[] buffer = new char[BUFFER_SIZE];
int length;
while ((length = reader.read(buffer)) != -1) {
builder.append(buffer, 0, length);
}
return builder.toString();
}
如果需要将字符串转换为没有外部库的特定字符集,则:
public String convertStreamToString(InputStream is) throws IOException {
try (ByteArrayOutputStream baos = new ByteArrayOutputStream();) {
is.transferTo(baos);
return baos.toString(StandardCharsets.UTF_8);
}
}
我已经写了一个这样的课,所以我想我会和大家分享。有时候,您不想仅仅为了一件事而添加Apache Commons,并且想要比Scanner更笨的东西,它不检查内容。
用法如下
// Read from InputStream
String data = new ReaderSink(inputStream, Charset.forName("UTF-8")).drain();
// Read from File
data = new ReaderSink(file, Charset.forName("UTF-8")).drain();
// Drain input stream to console
new ReaderSink(inputStream, Charset.forName("UTF-8")).drainTo(System.out);
以下是ReaderSink的代码:
import java.io.*;
import java.nio.charset.Charset;
/**
* A simple sink class that drains a {@link Reader} to a {@link String} or
* to a {@link Writer}.
*
* @author Ben Barkay
* @version 2/20/2014
*/
public class ReaderSink {
/**
* The default buffer size to use if no buffer size was specified.
*/
public static final int DEFAULT_BUFFER_SIZE = 1024;
/**
* The {@link Reader} that will be drained.
*/
private final Reader in;
/**
* Constructs a new {@code ReaderSink} for the specified file and charset.
* @param file The file to read from.
* @param charset The charset to use.
* @throws FileNotFoundException If the file was not found on the filesystem.
*/
public ReaderSink(File file, Charset charset) throws FileNotFoundException {
this(new FileInputStream(file), charset);
}
/**
* Constructs a new {@code ReaderSink} for the specified {@link InputStream}.
* @param in The {@link InputStream} to drain.
* @param charset The charset to use.
*/
public ReaderSink(InputStream in, Charset charset) {
this(new InputStreamReader(in, charset));
}
/**
* Constructs a new {@code ReaderSink} for the specified {@link Reader}.
* @param in The reader to drain.
*/
public ReaderSink(Reader in) {
this.in = in;
}
/**
* Drains the data from the underlying {@link Reader}, returning a {@link String} containing
* all of the read information. This method will use {@link #DEFAULT_BUFFER_SIZE} for
* its buffer size.
* @return A {@link String} containing all of the information that was read.
*/
public String drain() throws IOException {
return drain(DEFAULT_BUFFER_SIZE);
}
/**
* Drains the data from the underlying {@link Reader}, returning a {@link String} containing
* all of the read information.
* @param bufferSize The size of the buffer to use when reading.
* @return A {@link String} containing all of the information that was read.
*/
public String drain(int bufferSize) throws IOException {
StringWriter stringWriter = new StringWriter();
drainTo(stringWriter, bufferSize);
return stringWriter.toString();
}
/**
* Drains the data from the underlying {@link Reader}, writing it to the
* specified {@link Writer}. This method will use {@link #DEFAULT_BUFFER_SIZE} for
* its buffer size.
* @param out The {@link Writer} to write to.
*/
public void drainTo(Writer out) throws IOException {
drainTo(out, DEFAULT_BUFFER_SIZE);
}
/**
* Drains the data from the underlying {@link Reader}, writing it to the
* specified {@link Writer}.
* @param out The {@link Writer} to write to.
* @param bufferSize The size of the buffer to use when reader.
*/
public void drainTo(Writer out, int bufferSize) throws IOException {
char[] buffer = new char[bufferSize];
int read;
while ((read = in.read(buffer)) > -1) {
out.write(buffer, 0, read);
}
}
}
在Groovy中
inputStream.getText()