Java IO - DataFormatted
来源：互联网 发布：2017qq空间淘宝客推广 编辑：程序博客网 时间：2024/04/30 06:39
Java IO - DataFormatted
目录
- Java IO - DataFormatted
- 目录
- PrintStream
- PrintWriter
PrintStream 和 PrintWriter
PrintStream
package java.io;import java.util.Formatter;import java.util.Locale;import java.nio.charset.Charset;import java.nio.charset.IllegalCharsetNameException;import java.nio.charset.UnsupportedCharsetException;/** * PrintStream 是一个包装类，从名字上可以看出它可以提供各种数据的打印形式。 * 而且，PrintStream 不会抛出异常。再者，PrintStream 可以设置成自动 flush。 * 所有 PrintStream 打印的字符都会在底层被转变成字节(使用系统的默认编码)，如果想要写入字符，考虑使用 PrintWriter */public class PrintStream extends FilterOutputStream implements Appendable, Closeable{ private final boolean autoFlush; private boolean trouble = false; private Formatter formatter; /** * 底层使用的还是 BufferedWriter 和 OutputStreamWriter */ private BufferedWriter textOut; private OutputStreamWriter charOut; /** * PrintStream 在系统初始化的时候更早加载，所以为了不依赖 java.util.Objects.requireNonNull. 在这里事先定义了。 */ private static <T> T requireNonNull(T obj, String message) { if (obj == null) throw new NullPointerException(message); return obj; } /** * 给定字符集名称返回一个字符集对象. */ private static Charset toCharset(String csn) throws UnsupportedEncodingException { requireNonNull(csn, "charsetName"); try { return Charset.forName(csn); } catch (IllegalCharsetNameException|UnsupportedCharsetException unused) { // UnsupportedEncodingException should be thrown throw new UnsupportedEncodingException(csn); } } /* 给定 OutputStream，创建一个 PrintStream */ private PrintStream(boolean autoFlush, OutputStream out) { super(out); this.autoFlush = autoFlush; this.charOut = new OutputStreamWriter(this); this.textOut = new BufferedWriter(charOut); } private PrintStream(boolean autoFlush, OutputStream out, Charset charset) { super(out); this.autoFlush = autoFlush; this.charOut = new OutputStreamWriter(this, charset); this.textOut = new BufferedWriter(charOut); } // 为了优先校验 charset!!! private PrintStream(boolean autoFlush, Charset charset, OutputStream out) throws UnsupportedEncodingException { this(autoFlush, out, charset); } /** * 不会自动 刷新 */ public PrintStream(OutputStream out) { this(out, false); } public PrintStream(OutputStream out, boolean autoFlush) { this(autoFlush, requireNonNull(out, "Null output stream")); } public PrintStream(OutputStream out, boolean autoFlush, String encoding) throws UnsupportedEncodingException { this(autoFlush, requireNonNull(out, "Null output stream"), toCharset(encoding)); } public PrintStream(String fileName) throws FileNotFoundException { this(false, new FileOutputStream(fileName)); } public PrintStream(String fileName, String csn) throws FileNotFoundException, UnsupportedEncodingException { // ensure charset is checked before the file is opened this(false, toCharset(csn), new FileOutputStream(fileName)); } public PrintStream(File file) throws FileNotFoundException { this(false, new FileOutputStream(file)); } public PrintStream(File file, String csn) throws FileNotFoundException, UnsupportedEncodingException { // ensure charset is checked before the file is opened this(false, toCharset(csn), new FileOutputStream(file)); } /** Check to make sure that the stream has not been closed */ private void ensureOpen() throws IOException { if (out == null) throw new IOException("Stream closed"); } /** * 把缓存的所有数据写入到 outputstream 中，然后再刷新这个 outputstream */ public void flush() { synchronized (this) { try { ensureOpen(); out.flush(); } catch (IOException x) { trouble = true; } } } private boolean closing = false; /* To avoid recursive closing */ public void close() { synchronized (this) { if (! closing) { closing = true; try { textOut.close(); out.close(); // 先 flush } catch (IOException x) { trouble = true; } textOut = null; charOut = null; out = null; } } } public boolean checkError() { if (out != null) flush(); // 先 flush if (out instanceof java.io.PrintStream) { PrintStream ps = (PrintStream) out; return ps.checkError(); } return trouble; } protected void setError() { trouble = true; } protected void clearError() { trouble = false; } /* * Exception-catching, synchronized output operations, * which also implement the write() methods of OutputStream */ /** * 写一个字节，如果这个字节是 \n 并且 autoFlush 开启了，那么就flush输出流，下同 */ public void write(int b) { try { synchronized (this) { ensureOpen(); out.write(b); if ((b == '\n') && autoFlush) out.flush(); } } catch (InterruptedIOException x) { Thread.currentThread().interrupt(); } catch (IOException x) { trouble = true; } } public void write(byte buf[], int off, int len) { try { synchronized (this) { ensureOpen(); out.write(buf, off, len); if (autoFlush) // 只判断 autoFlush out.flush(); } } catch (InterruptedIOException x) { Thread.currentThread().interrupt(); } catch (IOException x) { trouble = true; } } /* * 文本和字符流直接就把数据刷到 outputstream中了 */ private void write(char buf[]) { try { synchronized (this) { ensureOpen(); textOut.write(buf); textOut.flushBuffer(); charOut.flushBuffer(); if (autoFlush) { for (int i = 0; i < buf.length; i++) if (buf[i] == '\n') out.flush(); } } } catch (InterruptedIOException x) { Thread.currentThread().interrupt(); } catch (IOException x) { trouble = true; } } private void write(String s) { try { synchronized (this) { ensureOpen(); textOut.write(s); textOut.flushBuffer(); charOut.flushBuffer(); if (autoFlush && (s.indexOf('\n') >= 0)) out.flush(); } } catch (InterruptedIOException x) { Thread.currentThread().interrupt(); } catch (IOException x) { trouble = true; } } private void newLine() { try { synchronized (this) { ensureOpen(); textOut.newLine(); textOut.flushBuffer(); charOut.flushBuffer(); if (autoFlush) out.flush(); } } catch (InterruptedIOException x) { Thread.currentThread().interrupt(); } catch (IOException x) { trouble = true; } } /* Methods that do not terminate lines */ /** * 打印一个 boolean 类型数据，实际写入的是 经过编码的字符串 */ public void print(boolean b) { write(b ? "true" : "false"); } /** * 打印一个字符，会被编码 */ public void print(char c) { write(String.valueOf(c)); } /** * 写入一个整形数字，产生的字符串会被编码 */ public void print(int i) { write(String.valueOf(i)); } public void print(long l) { write(String.valueOf(l)); } public void print(float f) { write(String.valueOf(f)); } public void print(double d) { write(String.valueOf(d)); } public void print(char s[]) { write(s); } public void print(String s) { if (s == null) { s = "null"; } write(s); } public void print(Object obj) { write(String.valueOf(obj)); } /* Methods that do terminate lines */ /** * 终结行，添加行结束符 */ public void println() { newLine(); } public void println(boolean x) { synchronized (this) { print(x); newLine(); } } public void println(char x) { synchronized (this) { print(x); newLine(); } } public void println(int x) { synchronized (this) { print(x); newLine(); } } public void println(long x) { synchronized (this) { print(x); newLine(); } } public void println(float x) { synchronized (this) { print(x); newLine(); } } public void println(double x) { synchronized (this) { print(x); newLine(); } } public void println(char x[]) { synchronized (this) { print(x); newLine(); } } public void println(String x) { synchronized (this) { print(x); newLine(); } } public void println(Object x) { String s = String.valueOf(x); synchronized (this) { print(s); newLine(); } } /** * 写入一个格式化的字符串到输出流中 * 这个方法与 out.format(format, args) 一毛一样 */ public PrintStream printf(String format, Object ... args) { return format(format, args); } public PrintStream printf(Locale l, String format, Object ... args) { return format(l, format, args); } public PrintStream format(String format, Object ... args) { try { synchronized (this) { ensureOpen(); if ((formatter == null) || (formatter.locale() != Locale.getDefault())) formatter = new Formatter((Appendable) this); formatter.format(Locale.getDefault(), format, args); } } catch (InterruptedIOException x) { Thread.currentThread().interrupt(); } catch (IOException x) { trouble = true; } return this; } public PrintStream format(Locale l, String format, Object ... args) { try { synchronized (this) { ensureOpen(); if ((formatter == null) || (formatter.locale() != l)) formatter = new Formatter(this, l); formatter.format(l, format, args); } } catch (InterruptedIOException x) { Thread.currentThread().interrupt(); } catch (IOException x) { trouble = true; } return this; } public PrintStream append(CharSequence csq) { if (csq == null) print("null"); else print(csq.toString()); return this; } public PrintStream append(CharSequence csq, int start, int end) { CharSequence cs = (csq == null ? "null" : csq); write(cs.subSequence(start, end).toString()); return this; } public PrintStream append(char c) { print(c); return this; }}PrintWriter
package java.io;import java.util.Objects;import java.util.Formatter;import java.util.Locale;import java.nio.charset.Charset;import java.nio.charset.IllegalCharsetNameException;import java.nio.charset.UnsupportedCharsetException;/** * 打印对象的格式化表现形式到一个文本输出流。 */public class PrintWriter extends Writer { /** * PrintWriter 底层的 Writer */ protected Writer out; private final boolean autoFlush; private boolean trouble = false; private Formatter formatter; private PrintStream psOut = null; private final String lineSeparator; /** * 给定 字符集名称，返回字符集对象。 */ private static Charset toCharset(String csn) throws UnsupportedEncodingException { Objects.requireNonNull(csn, "charsetName"); try { return Charset.forName(csn); } catch (IllegalCharsetNameException|UnsupportedCharsetException unused) { // UnsupportedEncodingException should be thrown throw new UnsupportedEncodingException(csn); } } public PrintWriter (Writer out) { this(out, false); } public PrintWriter(Writer out, boolean autoFlush) { super(out); this.out = out; this.autoFlush = autoFlush; lineSeparator = java.security.AccessController.doPrivileged( new sun.security.action.GetPropertyAction("line.separator")); } /** * 还可以包装 OutputStream 呢 */ public PrintWriter(OutputStream out) { this(out, false); } public PrintWriter(OutputStream out, boolean autoFlush) { this(new BufferedWriter(new OutputStreamWriter(out)), autoFlush); // save print stream for error propagation if (out instanceof java.io.PrintStream) { psOut = (PrintStream) out; } } /** * 使用默认的编码创建一个 PrintWriter，底层是 BufferedWriter */ public PrintWriter(String fileName) throws FileNotFoundException { this(new BufferedWriter(new OutputStreamWriter(new FileOutputStream(fileName))), false); } /* Private constructor */ private PrintWriter(Charset charset, File file) throws FileNotFoundException { this(new BufferedWriter(new OutputStreamWriter(new FileOutputStream(file), charset)), false); } public PrintWriter(String fileName, String csn) throws FileNotFoundException, UnsupportedEncodingException { this(toCharset(csn), new File(fileName)); } public PrintWriter(File file) throws FileNotFoundException { this(new BufferedWriter(new OutputStreamWriter(new FileOutputStream(file))), false); } public PrintWriter(File file, String csn) throws FileNotFoundException, UnsupportedEncodingException { this(toCharset(csn), file); } private void ensureOpen() throws IOException { if (out == null) throw new IOException("Stream closed"); } public void flush() { try { synchronized (lock) { ensureOpen(); out.flush(); } } catch (IOException x) { trouble = true; } } public void close() { try { synchronized (lock) { if (out == null) return; out.close(); out = null; } } catch (IOException x) { trouble = true; } } public boolean checkError() { if (out != null) { flush(); } if (out instanceof java.io.PrintWriter) { PrintWriter pw = (PrintWriter) out; return pw.checkError(); } else if (psOut != null) { return psOut.checkError(); } return trouble; } protected void setError() { trouble = true; } protected void clearError() { trouble = false; } public void write(int c) { try { synchronized (lock) { ensureOpen(); out.write(c); } } catch (InterruptedIOException x) { Thread.currentThread().interrupt(); } catch (IOException x) { trouble = true; } } public void write(char buf[], int off, int len) { try { synchronized (lock) { ensureOpen(); out.write(buf, off, len); } } catch (InterruptedIOException x) { Thread.currentThread().interrupt(); } catch (IOException x) { trouble = true; } } public void write(char buf[]) { write(buf, 0, buf.length); } public void write(String s, int off, int len) { try { synchronized (lock) { ensureOpen(); out.write(s, off, len); } } catch (InterruptedIOException x) { Thread.currentThread().interrupt(); } catch (IOException x) { trouble = true; } } public void write(String s) { write(s, 0, s.length()); } private void newLine() { try { synchronized (lock) { ensureOpen(); out.write(lineSeparator); if (autoFlush) out.flush(); } } catch (InterruptedIOException x) { Thread.currentThread().interrupt(); } catch (IOException x) { trouble = true; } } /* Methods that do not terminate lines */ public void print(boolean b) { write(b ? "true" : "false"); } public void print(char c) { write(c); } public void print(int i) { write(String.valueOf(i)); } public void print(long l) { write(String.valueOf(l)); } public void print(float f) { write(String.valueOf(f)); } public void print(double d) { write(String.valueOf(d)); } public void print(char s[]) { write(s); } public void print(String s) { if (s == null) { s = "null"; } write(s); } public void print(Object obj) { write(String.valueOf(obj)); } /* Methods that do terminate lines */ public void println() { newLine(); } public void println(boolean x) { synchronized (lock) { print(x); println(); } } public void println(char x) { synchronized (lock) { print(x); println(); } } public void println(int x) { synchronized (lock) { print(x); println(); } } public void println(long x) { synchronized (lock) { print(x); println(); } } public void println(float x) { synchronized (lock) { print(x); println(); } } public void println(double x) { synchronized (lock) { print(x); println(); } } public void println(char x[]) { synchronized (lock) { print(x); println(); } } public void println(String x) { synchronized (lock) { print(x); println(); } } public void println(Object x) { String s = String.valueOf(x); synchronized (lock) { print(s); println(); } } public PrintWriter printf(String format, Object ... args) { return format(format, args); } public PrintWriter printf(Locale l, String format, Object ... args) { return format(l, format, args); } public PrintWriter format(String format, Object ... args) { try { synchronized (lock) { ensureOpen(); if ((formatter == null) || (formatter.locale() != Locale.getDefault())) formatter = new Formatter(this); formatter.format(Locale.getDefault(), format, args); if (autoFlush) out.flush(); } } catch (InterruptedIOException x) { Thread.currentThread().interrupt(); } catch (IOException x) { trouble = true; } return this; } public PrintWriter format(Locale l, String format, Object ... args) { try { synchronized (lock) { ensureOpen(); if ((formatter == null) || (formatter.locale() != l)) formatter = new Formatter(this, l); formatter.format(l, format, args); if (autoFlush) out.flush(); } } catch (InterruptedIOException x) { Thread.currentThread().interrupt(); } catch (IOException x) { trouble = true; } return this; } public PrintWriter append(CharSequence csq) { if (csq == null) write("null"); else write(csq.toString()); return this; } public PrintWriter append(CharSequence csq, int start, int end) { CharSequence cs = (csq == null ? "null" : csq); write(cs.subSequence(start, end).toString()); return this; } public PrintWriter append(char c) { write(c); return this; }} 0 0
- Java IO - DataFormatted
- 【Java-IO】IO入门
- Java IO：IO框架
- 【IO】java IO 总结
- java IO
- IO.java
- JAVA IO
- JAVA IO
- java IO
- java io
- JAVA IO
- java IO
- java IO
- java io
- java io
- java io
- java IO
- java IO
- hibernate的saveOrUpdate方法
- Universal-Image-Loader源码阅读（39）-DefaultConfigurationFactory
- php下pthreads扩展安装
- ftp
- Java中finally与return的执行顺序
- Java IO - DataFormatted
- IO 的阻塞和非阻塞二：轮询操作
- CentOS 7 配置 MySQL 5.7
- 安装SVN步骤
- 项目中曾经出现的一些bug以及以后要注意的一些问题
- mysql远程连接很慢解决办法
- RecylerView滑动，拖拽
- mybatis实战教程(mybatis in action),mybatis入门到精通
- js 和jquery 操作radio 和checkbox
