Question

此类打开一个文件，在//处分隔并返回一个字符串。然后，我使用Matcher的模式集来搜索字符串并返回数据片段。稍后，这将用于将数据重新格式化为许多文件和特定订单。目前，这个过程已经处理了多个模式匹配，但是当我传递EditorList和AuthorList时，当数据显然存在时，它返回null。程序在尝试使用null字符串时崩溃，我得到一个空指针异常。这是我第一次使用Pattern和Matcher，我在这里忽略了什么显而易见的事情？

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class MatchMethod {
public static String cancerCat=null;    
public static String paperType="book";
public static String Paper=null;
public static String Title=null;
public static String Abstr=null;
public static String Publi=null;
public static String Editi=null;
public static String Pagen=null;
public static String Bookt=null;
public static String Years=null;
public static String Editl=null;
public static String Edito=null;
public static String Authl=null;
public static String Autho=null;
public static String Foren=null;
public static String Initi=null;
public static String Lastn=null;

public static Scanner scanner;
public static File file;

static Pattern PaperBegin = Pattern.compile("<PaperBegin>(.+?)</PaperBegin>");
static Pattern PaperTitle = Pattern.compile("<PaperTitle>(.+?)</PaperTitle>");
static Pattern Abstract =   Pattern.compile("<Abstract>(.+?)</Abstract>");
static Pattern BookTitle =  Pattern.compile("<BookTitle>(.+?)</BookTitle>");
static Pattern Publisher =  Pattern.compile("<Publisher>(.+?)</Publisher>");
static Pattern Edition =    Pattern.compile("<Edition>(.+?)</Edition>");
static Pattern Page =       Pattern.compile("<Page>(.+?)</Page>");
static Pattern EditorList = Pattern.compile("<EditorList>(.+?)</EditorList>");
static Pattern Editor =     Pattern.compile("<Editor>(.+?)</Editor>");
static Pattern Year =       Pattern.compile("<Year>(.+?)</Year>");   
static Pattern AuthorList = Pattern.compile("<AuthorList>(.+?)</AuthorList>");
static Pattern Author =     Pattern.compile("<Author>(.+?)</Author>");
static Pattern ForeName =   Pattern.compile("<ForeName>(.+?)</ForeName>");
static Pattern Initials =   Pattern.compile("<Initials>(.+?)</Initials>");
static Pattern LastName =   Pattern.compile("<LastName>(.+?)</LastName>");

public static String find (String text, Pattern pattern)
{
    String found=null;
    Matcher match = pattern.matcher(text);
    if (match.find()) {found = match.group(1);}
    System.out.println((pattern.toString()) + " found: "+found);
    return  found;
}

@SuppressWarnings("resource")
static void readBook (String book) throws FileNotFoundException
{
    file = new File (book);
    scanner = new Scanner(file).useDelimiter("\\//");
    while (scanner.hasNext()) 
    {           
        Paper=scanner.next();
        Title = find (Paper, PaperTitle);
        Abstr = find (Paper, Abstract);
        Publi = find (Paper, Publisher);
        Editi = find (Paper, Edition);
        Pagen = find (Paper, Page);
        Bookt = find (Paper, BookTitle);
        Years = find (Paper, Year);         
        Editl = find (Paper, EditorList);
        Authl = find (Paper, AuthorList);

        Matcher mEdito = Editor.matcher(Editl);
        Edito = mEdito.group(1);
        while (mEdito.find()) // while loop to find all editors
        {
            System.out.println("Searching editors");                
            Foren = find (Edito, ForeName);
            Initi = find (Edito, Initials);
            Lastn = find (Edito, LastName);
            System.out.println ("EDITORS: " + Bookt + "\t" + Foren + "\t" + Initi + "\t" + Lastn);
        }
        Matcher mAutho = Author.matcher(Authl);
        while (mAutho.find()) // while loop to find all editors
        {
            System.out.println("Searching authors");
            Autho = mAutho.group(1);
            Foren = find (Autho, ForeName);
            Initi = find (Autho, Initials);
            Lastn = find (Autho, LastName);
            System.out.println ("AUTHORS: " + Bookt + "\t" + Foren + "\t" + Initi + "\t" + Lastn);
        }   
    }
}

public static void main(String[] args) throws IOException 
{
    readBook ("CC_book.txt"); //opens text file to be mined


    //Start reading Colon Cancer Book Information

    //Start reading Endocrine Cancer Book Information

    //Start reading Lung Cancer Book Information

    //Start reading Other Cancer Book Information   

    //Start reading Pancreatic Cancer Book Information
    scanner.close();
}

}

以下是文件中的示例数据：

<PaperTitle>True incidence of all complications following immediate and delayed breast     reconstruction.</PaperTitle>
<Abstract>BACKGROUND: Improved self-image and psychological well-being after breast      reconstruction are well documented. To determine methods that optimized results with minimal morbidity, the authors examined their results and complications based on reconstruction method and timing. METHODS: The authors reviewed all breast reconstructions after mastectomy for breast cancer performed under the supervision of a single surgeon over a 6-year period at a tertiary referral center. Reconstruction method and timing, patient characteristics, and complication rates were reviewed. RESULTS: Reconstruction was performed on 240 consecutive women (94 bilateral and 146 unilateral; 334 total reconstructions). Reconstruction timing was evenly split between immediate (n = 167) and delayed (n = 167). Autologous tissue (n = 192) was more common than tissue expander/implant reconstruction (n = 142), and the free deep inferior epigastric perforator was the most common free flap (n = 124). The authors found no difference in the complication incidence with autologous reconstruction, whether performed immediately or delayed. However, there was a significantly higher complication rate following immediate placement of a tissue expander when compared with delayed reconstruction (p = 0.008). Capsular contracture was a significantly more common late complication following immediate (40.4 percent) versus delayed (17.0 percent) reconstruction (p &lt; 0.001; odds ratio, 5.2; 95 percent confidence interval, 2.3 to 11.6). CONCLUSIONS: Autologous reconstruction can be performed immediately or delayed, with optimal aesthetic outcome and low flap loss risk. However, the overall complication and capsular contracture incidence following immediate tissue expander/implant reconstruction was much higher than when performed delayed. Thus, tissue expander placement at the time of mastectomy may not necessarily save the patient an extra operation and may compromise the final aesthetic outcome.</Abstract>
<BookTitle>Book1</BookTitle>
<Publisher>Publisher01, Boston</Publisher>
<Edition>1st</Edition>
<EditorList>
<Editor>
    <LastName>Lewis</LastName>
    <ForeName>Philip M</ForeName>
    <Initials>PM</Initials>
</Editor>
<Editor>
    <LastName>Kiffer</LastName>
    <ForeName>Michael</ForeName>
    <Initials>M</Initials>
</Editor>
</EditorList>
<Page>19-28</Page>
<Year>2008</Year>
<AuthorList>
            <Author ValidYN="Y">
                <LastName>Sullivan</LastName>
                <ForeName>Stephen R</ForeName>
                <Initials>SR</Initials>
            </Author>
            <Author ValidYN="Y">
                <LastName>Fletcher</LastName>
                <ForeName>Derek R D</ForeName>
                <Initials>DR</Initials>
            </Author>
            <Author ValidYN="Y">
                <LastName>Isom</LastName>
                <ForeName>Casey D</ForeName>
                <Initials>CD</Initials>
            </Author>
            <Author ValidYN="Y">
                <LastName>Isik</LastName>
                <ForeName>F Frank</ForeName>
                <Initials>FF</Initials>
            </Author>
</AuthorList>
//
<PaperTitle>Polygenes, risk prediction, and targeted prevention of breast cancer.</PaperTitle>
<Abstract>BACKGROUND: New developments in the search for susceptibility alleles in complex disorders provide support for the possibility of a polygenic approach to the prevention and treatment of common diseases. METHODS: We examined the implications, both for individualized disease prevention and for public health policy, of findings concerning the risk of breast cancer that are based on common genetic variation. RESULTS: Our analysis suggests that the risk profile generated by the known, common, moderate-risk alleles does not provide sufficient discrimination to warrant individualized prevention. However, useful risk stratification may be possible in the context of programs for disease prevention in the general population. CONCLUSIONS: The clinical use of single, common, low-penetrance genes is limited, but a few susceptibility alleles may distinguish women who are at high risk for breast cancer from those who are at low risk, particularly in the context of population screening.</Abstract>
<BookTitle>Book2</BookTitle>
<Publisher>Publisher02, New York</Publisher>
<Edition>3rd</Edition>
<EditorList>
<Editor>
    <LastName>Bernstein</LastName>
    <ForeName>Arthur</ForeName>
    <Initials>A</Initials>
</Editor>
</EditorList>
<Page>2796-803</Page>
<Year>2008</Year>
<AuthorList>
            <Author ValidYN="Y">
                <LastName>Pharoah</LastName>
                <ForeName>Paul D P</ForeName>
                <Initials>PD</Initials>
            </Author>
            <Author ValidYN="Y">
                <LastName>Antoniou</LastName>
                <ForeName>Antonis C</ForeName>
                <Initials>AC</Initials>
            </Author>
            <Author ValidYN="Y">
                <LastName>Easton</LastName>
                <ForeName>Douglas F</ForeName>
                <Initials>DF</Initials>
            </Author>
            <Author ValidYN="Y">
                <LastName>Ponder</LastName>
                <ForeName>Bruce A J</ForeName>
                <Initials>BA</Initials>
            </Author>
</AuthorList>
//
<PaperTitle>Invasive breast cancer: predicting disease recurrence by using high-spatial-resolution signal enhancement ratio imaging.</PaperTitle>
<Abstract>PURPOSE: To retrospectively evaluate high-spatial-resolution signal enhancement ratio (SER) imaging for the prediction of disease recurrence in patients with breast cancer who underwent preoperative magnetic resonance (MR) imaging. MATERIALS AND METHODS: This retrospective study was approved by the institutional review board and was HIPAA compliant; informed consent was waived. From 1995 to 2002, gadolinium-enhanced MR imaging data were acquired with a three time point high-resolution method in women undergoing neoadjuvant therapy for invasive breast cancers. Forty-eight women (mean age, 49.1 years; range, 29.7-72.4 years) were divided into recurrence-free or recurrence groups. Volume measurements were tabulated for SER values between set ranges; cutoff criteria were defined to predict disease recurrence after surgery. Wilcoxon rank sum tests and the multivariate Cox proportional hazards regression model were used for evaluation. RESULTS: Breast tumor volume calculated from the number of voxels with SER values above a threshold corresponding to the upper limit of mean redistribution rate constant in benign tumors (0.88 minutes(-1)) and the volume of cancerous breast tissue infiltrating into the parenchyma were important predictors of disease recurrence. Seventy-five percent of patients with recurrence and 100% of deceased patients were identified as being at high risk for recurrence. Thirty percent of patients with recurrence and 67% of deceased patients were identified as having high risk before chemotherapy. No patients in the recurrence-free group were misidentified as likely to have recurrence. All three prechemotherapy parameters (total tumor volume, tumor volumes with high and low SER) and the postchemotherapy tumor volume with high SER were significantly different between the two groups. The multivariate Cox proportional hazards regression showed that, of the three prechemotherapy covariates, only the low SER and high SER tumor volumes (P = .017 and .049, respectively) were significant and independent predictors of tumor recurrence. Tumor volume with high SER was the only significant postchemotherapy covariate predictor (P = .038). CONCLUSION: High-spatial-resolution SER imaging may improve prediction for patients at high risk for disease recurrence and death.</Abstract>
<BookTitle>Book3</BookTitle>
<Publisher>Publisher03, London</Publisher>
<Edition>3rd</Edition>
<EditorList>
<Editor>
    <LastName>Anderson</LastName>
    <ForeName>John T</ForeName>
    <Initials>JT</Initials>
</Editor>
<Editor>
    <LastName>Hoffman</LastName>
    <ForeName>John A</ForeName>
    <Initials>JA</Initials>
</Editor>
<Editor>
    <LastName>Smithson</LastName>
    <ForeName>Joshua H</ForeName>
    <Initials>JH</Initials>
</Editor>
</EditorList>
<Page>79-87</Page>
<Year>2008</Year>
<AuthorList>
            <Author ValidYN="Y">
                <LastName>Li</LastName>
                <ForeName>Ka-Loh</ForeName>
                <Initials>KL</Initials>
            </Author>
            <Author ValidYN="Y">
                <LastName>Partridge</LastName>
                <ForeName>Savannah C</ForeName>
                <Initials>SC</Initials>
            </Author>
            <Author ValidYN="Y">
                <LastName>Joe</LastName>
                <ForeName>Bonnie N</ForeName>
                <Initials>BN</Initials>
            </Author>
            <Author ValidYN="Y">
                <LastName>Gibbs</LastName>
                <ForeName>Jessica E</ForeName>
                <Initials>JE</Initials>
            </Author>
            <Author ValidYN="Y">
                <LastName>Lu</LastName>
                <ForeName>Ying</ForeName>
                <Initials>Y</Initials>
            </Author>
            <Author ValidYN="Y">
                <LastName>Esserman</LastName>
                <ForeName>Laura J</ForeName>
                <Initials>LJ</Initials>
            </Author>
            <Author ValidYN="Y">
                <LastName>Hylton</LastName>
                <ForeName>Nola M</ForeName>
                <Initials>NM</Initials>
            </Author>
</AuthorList>
//

Answer 1

我知道java必须有很多工具来解析xml，并且用regex解析xml，除了很多东西之外，还会变得非常混乱。

我不是java程序员，但你可能会遇到。默认情况下不匹配换行符。您可以使用开关(?s)为所有正则表达前缀，该开关实际上仅适用于编辑器，作者，编辑列表和作者列表。

例如，你的作者正则表达式看起来像这样。

static Pattern Author = Pattern.compile("(?s)<Author>(.+?)</Author>");

来源： Regular expression does not match newline obtained from Formatter object

关于您评论的内容

...这是另一个问题，因为如果它是空的，它应该只返回另一个空字符串。 ...

你的正则表达不会这样做是因为你正在使用（。+？）。如果您将每次出现的情况（如果适用）更改为(.*?)，则允许空字符串。。+需要开始和结束标记之间的字符（任何字符）。。*不需要角色，但抓住任何礼物。而且？使匹配非贪婪，以便在符合标准时立即捕获。

Consider the string: I like cats, I wonder if you like cats
"I (.*) cats" matches the whole string.
"I (.*?) cats" matches "I like cats", and if  the global flag is on, seperately matches "I wonder if you like cats"

您确定AuthorList / EditorList正在崩溃吗？

您的Author正则表达式根本没有考虑属性ValidYN，但此示例数据中的每个实例都包含它，因此您应该匹配它。

Author正则表达式尝试

<Author(?: [\w\-]*="[^"]*")*>(.+?)</Author>

这是一个简单的模式，用于查找属性中包含字母，数字，_或连字符的属性以及不能包含引号的带引号的属性。

或者，更简单一点，如果ValidYN是你唯一的属性：

<Author ValidYN="(?:Y|N)">(.+?)</Author>

然而，第一个正则表达式可能会与其他可能具有属性的标记进行交易，如果出现该问题的话。

Answer 2

任何群组只能在找到（或匹配或寻找）之后获得。

    Matcher mEdito = Editor.matcher(Editl);
    Edito = mEdito.group(1);
    while (mEdito.find()) // while loop to find all editors
    {

必须

    Matcher mEdito = Editor.matcher(Editl);
    while (mEdito.find()) // while loop to find all editors
    {
        Edito = mEdito.group(1);

P.S，

JAXB允许在java对象（类Author，Editor等）中读取此XML。

我看到你需要正则表达式.来匹配换行符。这是DOT_ALL选项，可以在正则表达式中以(?s)命令（“单行”）写入。

static Pattern EditorList = Pattern.compile("(?s)<EditorList>(.+?)</EditorList>");
...
static Pattern AuthorList = Pattern.compile("(?s)<AuthorList>(.+?)</AuthorList>");

Java Pattern Matcher在完成九个之前的类似模式/匹配后返回null

2 个答案: