org.springframework.boot.devtools.livereload.ConnectionInputStream.java Source code

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Here is the source code for org.springframework.boot.devtools.livereload.ConnectionInputStream.java

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/*
 * Copyright 2012-2019 the original author or authors.
 *
 * 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
 *
 *      https://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 org.springframework.boot.devtools.livereload;

import java.io.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;

/**
 * {@link InputStream} for a server connection.
 *
 * @author Phillip Webb
 */
class ConnectionInputStream extends FilterInputStream {

    private static final String HEADER_END = "\r\n\r\n";

    private static final int BUFFER_SIZE = 4096;

    ConnectionInputStream(InputStream in) {
        super(in);
    }

    /**
     * Read the HTTP header from the {@link InputStream}. Note: This method doesn't expect
     * any HTTP content after the header since the initial request is usually just a
     * WebSocket upgrade.
     * @return the HTTP header
     * @throws IOException in case of I/O errors
     */
    String readHeader() throws IOException {
        byte[] buffer = new byte[BUFFER_SIZE];
        StringBuilder content = new StringBuilder(BUFFER_SIZE);
        while (content.indexOf(HEADER_END) == -1) {
            int amountRead = checkedRead(buffer, 0, BUFFER_SIZE);
            content.append(new String(buffer, 0, amountRead));
        }
        return content.substring(0, content.indexOf(HEADER_END));
    }

    /**
     * Repeatedly read the underlying {@link InputStream} until the requested number of
     * bytes have been loaded.
     * @param buffer the destination buffer
     * @param offset the buffer offset
     * @param length the amount of data to read
     * @throws IOException in case of I/O errors
     */
    void readFully(byte[] buffer, int offset, int length) throws IOException {
        while (length > 0) {
            int amountRead = checkedRead(buffer, offset, length);
            offset += amountRead;
            length -= amountRead;
        }
    }

    /**
     * Read a single byte from the stream (checking that the end of the stream hasn't been
     * reached.
     * @return the content
     * @throws IOException in case of I/O errors
     */
    int checkedRead() throws IOException {
        int b = read();
        if (b == -1) {
            throw new IOException("End of stream");
        }
        return (b & 0xff);
    }

    /**
     * Read a number of bytes from the stream (checking that the end of the stream hasn't
     * been reached).
     * @param buffer the destination buffer
     * @param offset the buffer offset
     * @param length the length to read
     * @return the amount of data read
     * @throws IOException in case of I/O errors
     */
    int checkedRead(byte[] buffer, int offset, int length) throws IOException {
        int amountRead = read(buffer, offset, length);
        if (amountRead == -1) {
            throw new IOException("End of stream");
        }
        return amountRead;
    }

}