Druid/src/main/java/com/alibaba/druid/util/IOUtils.java

/*
 * Copyright 1999-2011 Alibaba Group Holding Ltd.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.alibaba.druid.util;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.Reader;
import java.io.StringWriter;
import java.io.UnsupportedEncodingException;
import java.lang.management.ManagementFactory;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Properties;

public class IOUtils {

    public final static int DEFAULT_BUFFER_SIZE = 1024 * 4;

    public static String read(InputStream in) {
        InputStreamReader reader;
        try {
            reader = new InputStreamReader(in, "UTF-8");
        } catch (UnsupportedEncodingException e) {
            throw new IllegalStateException(e.getMessage(), e);
        }
        return read(reader);
    }

    public static String readFromResource(String resource) throws IOException {
        InputStream in = null;
        try {
            in = Thread.currentThread().getContextClassLoader().getResourceAsStream(resource);
            if (in == null) {
                in = IOUtils.class.getResourceAsStream(resource);
            }

            if (in == null) {
                return null;
            }

            String text = IOUtils.read(in);
            return text;
        } finally {
            JdbcUtils.close(in);
        }
    }

    public static byte[] readByteArrayFromResource(String resource) throws IOException {
        InputStream in = null;
        try {
            in = Thread.currentThread().getContextClassLoader().getResourceAsStream(resource);
            if (in == null) {
                return null;
            }

            return readByteArray(in);
        } finally {
            JdbcUtils.close(in);
        }
    }

    public static byte[] readByteArray(InputStream input) throws IOException {
        ByteArrayOutputStream output = new ByteArrayOutputStream();
        copy(input, output);
        return output.toByteArray();
    }

    public static long copy(InputStream input, OutputStream output) throws IOException {
        final int EOF = -1;

        byte[] buffer = new byte[DEFAULT_BUFFER_SIZE];

        long count = 0;
        int n = 0;
        while (EOF != (n = input.read(buffer))) {
            output.write(buffer, 0, n);
            count += n;
        }
        return count;
    }

    public static String read(Reader reader) {
        try {

            StringWriter writer = new StringWriter();

            char[] buffer = new char[DEFAULT_BUFFER_SIZE];
            int n = 0;
            while (-1 != (n = reader.read(buffer))) {
                writer.write(buffer, 0, n);
            }

            return writer.toString();
        } catch (IOException ex) {
            throw new IllegalStateException("read error", ex);
        }
    }

    public static String read(Reader reader, int length) {
        try {
            char[] buffer = new char[length];

            int offset = 0;
            int rest = length;
            int len;
            while ((len = reader.read(buffer, offset, rest)) != -1) {
                rest -= len;
                offset += len;

                if (rest == 0) {
                    break;
                }
            }

            return new String(buffer, 0, length - rest);
        } catch (IOException ex) {
            throw new IllegalStateException("read error", ex);
        }
    }

    public static String toString(java.util.Date date) {
        if (date == null) {
            return null;
        }
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        return format.format(date);
    }

    public static String getStackTrace(Throwable ex) {
        StringWriter buf = new StringWriter();
        ex.printStackTrace(new PrintWriter(buf));

        return buf.toString();
    }

    public static String toString(StackTraceElement[] stackTrace) {
        StringBuilder buf = new StringBuilder();
        for (StackTraceElement item : stackTrace) {
            buf.append(item.toString());
            buf.append("\n");
        }
        return buf.toString();
    }

    public static Boolean getBoolean(Properties properties, String key) {
        String property = properties.getProperty(key);
        if ("true".equals(property)) {
            return Boolean.TRUE;
        } else if ("false".equals(property)) {
            return Boolean.FALSE;
        }
        return null;
    }

    public static Integer getInteger(Properties properties, String key) {
        String property = properties.getProperty(key);

        if (property == null) {
            return null;
        }
        try {
            return Integer.parseInt(property);
        } catch (NumberFormatException ex) {
            // skip
        }
        return null;
    }

    public static Long getLong(Properties properties, String key) {
        String property = properties.getProperty(key);

        if (property == null) {
            return null;
        }
        try {
            return Long.parseLong(property);
        } catch (NumberFormatException ex) {
            // skip
        }
        return null;
    }

    public static Class<?> loadClass(String className) {
        Class<?> clazz = null;

        if (className == null) {
            return null;
        }

        ClassLoader ctxClassLoader = Thread.currentThread().getContextClassLoader();
        if (ctxClassLoader != null) {
            try {
                clazz = ctxClassLoader.loadClass(className);
            } catch (ClassNotFoundException e) {
                // skip
            }
        }

        if (clazz != null) {
            return clazz;
        }

        try {
            return Class.forName(className);
        } catch (ClassNotFoundException e) {
            return null;
        }
    }

    private static int pid;

    public final static int getPID() {
        if (pid == 0) {
            String name = ManagementFactory.getRuntimeMXBean().getName();

            String[] items = name.split("@");

            pid = Integer.parseInt(items[0]);
        }

        return pid;
    }

    private static Date startTime;

    public final static Date getStartTime() {
        if (startTime == null) {
            startTime = new Date(ManagementFactory.getRuntimeMXBean().getStartTime());
        }
        return startTime;
    }
}