在 Java 中生成格式化的差异输出java-diff-utils

java diff

2022-09-02 04:20:25

是否有任何适用于Java的库可以接受两个字符串，并根据*nix diff命令返回具有格式化输出的字符串？

例如：进料

test 1,2,3,4
test 5,6,7,8
test 9,10,11,12
test 13,14,15,16

和

test 1,2,3,4
test 5,6,7,8
test 9,10,11,12,13
test 13,14,15,16

作为输入，它会给你

test 1,2,3,4                                                    test 1,2,3,4
test 5,6,7,8                                                    test 5,6,7,8
test 9,10,11,12                                               | test 9,10,11,12,13
test 13,14,15,16                                                test 13,14,15,16

与我已将文件传递给完全相同diff -y expected actual

我发现了这个问题，它为一般的库提供了一些很好的建议，可以给你编程输出，但我想要直字符串结果。

我可以直接调用作为系统调用，但是这个特定的应用程序将在unix和Windows上运行，我无法确定环境是否真的可用。diffdiff

答案 1

java-diff-utils

DiffUtils 库，用于计算差异、应用补丁、在 Java 中生成并排视图

Diff Utils库是一个开源库，用于执行文本之间的比较操作：计算差异，应用补丁，生成统一的差异或解析它们，生成差异输出以便将来轻松显示（如并排视图）等等。

构建此库的主要原因是缺乏易于使用的库，其中包含处理diff文件时所需的所有常用内容。最初它的灵感来自JRCS库，它是diff模块的漂亮设计。

主要特点

计算两个文本之间的差异。

能够比普通的ascci手更多。使用此库，正确实现 hashCode（）和 equals（）的任何类型的数组或列表都可能受到差异的影响

修补并取消修补文本与给定的补丁

解析统一的差异格式

产生人类可读的差异

答案 2

我最终自己滚动。不确定它是否是最好的实现，而且它丑陋得像地狱一样，但它通过了测试输入。

它使用java-diff来完成繁重的差异提升（任何apache commons StrBuilder和StringUtils，而不是现有的Java StringBuilder）

public static String diffSideBySide(String fromStr, String toStr){
    // this is equivalent of running unix diff -y command
    // not pretty, but it works. Feel free to refactor against unit test.
    String[] fromLines = fromStr.split("\n");
    String[] toLines = toStr.split("\n");
    List<Difference> diffs = (new Diff(fromLines, toLines)).diff();

    int padding = 3;
    int maxStrWidth = Math.max(maxLength(fromLines), maxLength(toLines)) + padding;

    StrBuilder diffOut = new StrBuilder();
    diffOut.setNewLineText("\n");
    int fromLineNum = 0;
    int toLineNum = 0;
    for(Difference diff : diffs) {
        int delStart = diff.getDeletedStart();
        int delEnd = diff.getDeletedEnd();
        int addStart = diff.getAddedStart();
        int addEnd = diff.getAddedEnd();

        boolean isAdd = (delEnd == Difference.NONE && addEnd != Difference.NONE);
        boolean isDel = (addEnd == Difference.NONE && delEnd != Difference.NONE);
        boolean isMod = (delEnd != Difference.NONE && addEnd != Difference.NONE);

        //write out unchanged lines between diffs
        while(true) {
            String left = "";
            String right = "";
            if (fromLineNum < (delStart)){
                left = fromLines[fromLineNum];
                fromLineNum++;
            }
            if (toLineNum < (addStart)) {
                right = toLines[toLineNum];
                toLineNum++;
            }
            diffOut.append(StringUtils.rightPad(left, maxStrWidth));
            diffOut.append("  "); // no operator to display
            diffOut.appendln(right);

            if( (fromLineNum == (delStart)) && (toLineNum == (addStart))) {
                break;
            }
        }

        if (isDel) {
            //write out a deletion
            for(int i=delStart; i <= delEnd; i++) {
                diffOut.append(StringUtils.rightPad(fromLines[i], maxStrWidth));
                diffOut.appendln("<");
            }
            fromLineNum = delEnd + 1;
        } else if (isAdd) {
            //write out an addition
            for(int i=addStart; i <= addEnd; i++) {
                diffOut.append(StringUtils.rightPad("", maxStrWidth));
                diffOut.append("> ");
                diffOut.appendln(toLines[i]);
            }
            toLineNum = addEnd + 1; 
        } else if (isMod) {
            // write out a modification
            while(true){
                String left = "";
                String right = "";
                if (fromLineNum <= (delEnd)){
                    left = fromLines[fromLineNum];
                    fromLineNum++;
                }
                if (toLineNum <= (addEnd)) {
                    right = toLines[toLineNum];
                    toLineNum++;
                }
                diffOut.append(StringUtils.rightPad(left, maxStrWidth));
                diffOut.append("| ");
                diffOut.appendln(right);

                if( (fromLineNum > (delEnd)) && (toLineNum > (addEnd))) {
                    break;
                }
            }
        }

    }

    //we've finished displaying the diffs, now we just need to run out all the remaining unchanged lines
    while(true) {
        String left = "";
        String right = "";
        if (fromLineNum < (fromLines.length)){
            left = fromLines[fromLineNum];
            fromLineNum++;
        }
        if (toLineNum < (toLines.length)) {
            right = toLines[toLineNum];
            toLineNum++;
        }
        diffOut.append(StringUtils.rightPad(left, maxStrWidth));
        diffOut.append("  "); // no operator to display
        diffOut.appendln(right);

        if( (fromLineNum == (fromLines.length)) && (toLineNum == (toLines.length))) {
            break;
        }
    }

    return diffOut.toString();
}

private static int maxLength(String[] fromLines) {
    int maxLength = 0;

    for (int i = 0; i < fromLines.length; i++) {
        if (fromLines[i].length() > maxLength) {
            maxLength = fromLines[i].length();
        }
    }
    return maxLength;
}