http断点续传简单实现（java)

/* t]HY@@0g  
**SiteFileFetch.java yXU.PSG*  
*/ nQc,^A)I  
package NetFox; +4 k=Y  
import java.io.*; 'D21A8*N  
import java.net.*; x*1wsA  
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public class SiteFileFetch extends Thread { N`
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SiteInfoBean siteInfoBean = null; //文件信息Bean JV~ Dly>  
long[] nStartPos; //开始位置 )Q1>j 2&  
long[] nEndPos; //结束位置 # 55>?  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 i(.e=  
long nFileLength; //文件长度 RBQ8+^  
boolean bFirst = true; //是否第一次取文件 +(*HDa
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boolean bStop = false; //停止标志 A4"TJZBg}  
File tmpFile; //文件下载的临时信息 NsB]f{7>8+  
DataOutputStream output; //输出到文件的输出流 19$A!kH\  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） }y6|H,t9  
public SiteFileFetch(SiteInfoBean bean) throws IOException %Y&48''"  
{ M/ 64`lcb  
siteInfoBean = bean; j!4{+&Laq  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); kp*v:*  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); I# tlaz#  
if(tmpFile.exists ()) -DkD*64wu  
{  ;+~5XLk  
bFirst = false; .`IhxE~mN  
read_nPos(); h`6 (Oo|  
} u IXA{89  
else <q7o"NI6FZ  
{ <H^jbK  
nStartPos = new long[bean.getNSplitter()]; mz0{eO  
nEndPos = new long[bean.getNSplitter()]; f\ P0%  
} ,[;O'g?,g  
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} Q+B
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public void run() H@(O{ 9Yl;  
{ 3H,x4L5j  
//获得文件长度 `Abd=1nH  
//分割文件 LGhK)]:  
//实例FileSplitterFetch j-9)Sijj{  
//启动FileSplitterFetch线程 cM%?Ot,mK"  
//等待子线程返回 pN^
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try{ #aX#gh}1  
if(bFirst) Z1,rN#p9  
{ 5{HF'1XgZ*  
nFileLength = getFileSize(); H q
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if(nFileLength == -1) UV2W~g  
{ }R;}d(C`  
System.err.println("File Length is not known!"); 1WtE
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} "w?0f["  
else if(nFileLength == -2) tl_
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{ @g#5d|U);  
System.err.println("File is not access!"); ejd_ 85$  
} $2uC%er"H  
else ?!Y_w2  
{ Z#}sK5s  
for(int i=0;i<nStartPos.length;i++) %UI^+:C  
{ j/aJDE(+  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); kEh\@x[  
} 4ior  
for(int i=0;i<nEndPos.length-1;i++) ovp/DM  
{ Qhj']>#g  
nEndPos = nStartPos[i+1]; ddgDq0N1j  
} !SK`!/7c?  
nEndPos[nEndPos.length-1] = nFileLength; X2V+c
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} ;y(;7n_ a  
} 9JdJn>  
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//启动子线程 I7_8oq\3D  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; qIJc\,'  
for(int i=0;i<nStartPos.length;i++) G y[5'J
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{ _|\X8o_  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 0f5
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siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), W/UA%We3+L  
nStartPos,nEndPos,i); 0m3hL~0(a  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); Zv}F?4T~:  
fileSplitterFetch.start(); brTNwRze  
} H|aFs.SEQ  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), b"$?(Y  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); -. *E<%  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", CW
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nEndPos = " + nFileLength); .'=S1|_(  
// fileSplitterFetch[nPos.length-1].start(); Sqi9'-%m  
7@"X?u
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//等待子线程结束 `!cdxKLR  
//int count = 0; #;8)UNc)}  
//是否结束while循环 9&r]k8K
  
boolean breakWhile = false; }36AeJ7L  
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while(!bStop) Tbm ~@k(C  
{ #U-y<[ 3  
write_nPos(); "&H'?N%9Up  
Utility.sleep(500); A_TaXl(  
breakWhile = true; -G>J  
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for(int i=0;i<nStartPos.length;i++) jvQ^Vh!mC  
{ *m
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if(!fileSplitterFetch.bDownOver) {*;8`+R&  
{ K\ Wzh;  
breakWhile = false; bYLYJ`hH<R  
break; x"Ll/E)\v]  
} N?m)u,6-l  
} 9
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if(breakWhile) IiniaVuQ  
break; <%.%q  
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//count++; cS Lj\'`b  
//if(count>4) U~=?I)Ni  
// siteStop(); 2W0nA t  
} @Nb/
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System.err.println("文件下载结束！"); <SJ6<'  
} I._ A  
catch(Exception e){e.printStackTrace ();} }eSy]r[J  
} =( ZOn=IL  
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/ ^)3V
}  
//获得文件长度 *Z"cXg^ti  
public long getFileSize()
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{ =ttD5p  
int nFileLength = -1; *i*\dl  
try{ ^n
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URL url = new URL(siteInfoBean.getSSiteURL()); lO\HchGzB  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); WCd:(8B  
httpConnection.setRequestProperty("User-Agent","NetFox"); +E9G"Z65iP  
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,W+=N"`a'  
int responseCode=httpConnection.getResponseCode(); ,l AZ4  
if(responseCode>=400)  gwIR3u  
{ V(kK2az  
processErrorCode(responseCode); N^B7<~ bD  
return -2; //-2 represent access is error +8ib928E  
} $G <r2lPy  
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String sHeader; N'{Yhx u  
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for(int i=1;;i++) &(<>} r  
{ ,L  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); l'<&H#A;'  
//Utility.log(in.readLine()); PO5,lcBD<  
sHeader=httpConnection.getHeaderFieldKey(i); \roJf&O }  
if(sHeader!=null) pGU.+[|(  
{ W0x9^'=s\  
if(sHeader.equals("Content-Length")) v8)wu=u  
{ Ib{#dhV  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); 7>i
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break; %_n%-Qn  
} An>ai N
]  
} +D @B eQu  
else b`%u}^B {  
break; <- sr&  
} \6GNKeN  
} V%[t'uh  
catch(IOException e){e.printStackTrace ();} {_W8Qm`.  
catch(Exception e){e.printStackTrace ();} U}HSL5v  
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Utility.log(nFileLength); nv0D4 t  
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return nFileLength; tHaHBx1P  
} LTBH/[q5  
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//保存下载信息（文件指针位置） |63uoRr  
private void write_nPos() ~9rNP{+  
{ 5fs,UH  
try{ k2loGvBJ  
output = new DataOutputStream(new FileOutputStream(tmpFile)); F+VNrt-  
output.writeInt(nStartPos.length); U5ph4G  
for(int i=0;i<nStartPos.length;i++) VQf^yq  
{ Uth+4A
q  
// output.writeLong(nPos); $C=XSuPNK  
output.writeLong(fileSplitterFetch.nStartPos); w)K547!00  
output.writeLong(fileSplitterFetch.nEndPos); lNc0znY  
} m%eCTpYo  
output.close(); =ZoNkj/^,  
} 4T52vM  
catch(IOException e){e.printStackTrace ();} yS K81`  
catch(Exception e){e.printStackTrace ();} `tO t+>YWn  
} *:\[;69[  
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<% mD#S
 
//读取保存的下载信息（文件指针位置） 6;~V@t  
private void read_nPos() o S{hv:
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{ b!MN QGs  
try{ 1Cc91  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); /xSJljexz  
int nCount = input.readInt(); {B#w9>'b  
nStartPos = new long[nCount]; zGme}z;1@  
nEndPos = new long[nCount]; KN@ [hb7%  
for(int i=0;i<nStartPos.length;i++) i.K!;E>  
{ r25VcY
  
nStartPos = input.readLong(); LIJ#nb  
nEndPos = input.readLong(); !iHC++D  
} NG\'Ii:-J  
input.close(); N?S;v&q+  
} 'G[G;?F  
catch(IOException e){e.printStackTrace ();} l`6.(6  
catch(Exception e){e.printStackTrace ();} 5`}za-  
} O)R}|  
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private void processErrorCode(int nErrorCode) e7n0=U0  
{ TSJeS`I  
System.err.println("Error Code : " + nErrorCode); C:AV?  
} wYFkGih  
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//停止文件下载 <7T}b95  
public void siteStop() ;9#W#/B  
{ v}5YUM0H`  
bStop = true; *E>R1bJ8  
for(int i=0;i<nStartPos.length;i++) g>7i2  
fileSplitterFetch.splitterStop(); 67H?xsk@n  
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} 9A{D<h}yk  
} n}9<7e~/  
//负责部分文件的抓取 8t< X  
**FileSplitterFetch.java ,[N(XstI  
*/ Q|VBH5}1O  
package NetFox; X16O9qsh  
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import java.io.*; fhdqes])  
import java.net.*; fwx^?/5j  
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public class FileSplitterFetch extends Thread { E>E^t=;[  
2!9W:I7  
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String sURL; //File URL $zhvI*0  
long nStartPos; //File Snippet Start Position >X[:(m'  
long nEndPos; //File Snippet End Position ut]&3f''  
int nThreadID; //Thread's ID iBWEZw)  
boolean bDownOver = false; //Downing is over 7On.y*  
boolean bStop = false; //Stop identical lHliMBSc  
FileAccessI fileAccessI = null; //File Access interface $t6t 6<M)  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException `6YN/"unfp  
{ ]m&Ss  
this.sURL = sURL; ?|`n&HrP  
this.nStartPos = nStart; Az(,Q$"|5  
this.nEndPos = nEnd; gDw(_KC  
nThreadID = id; 2cS94h  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 TZn5s~t  
} G&Yo2aADR  
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public void run() x~IrqdmW  
{ ~rq:I<5  
while(nStartPos < nEndPos && !bStop) Xmb##:  
{ e<8KZ  
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try{ +?QHSIQo  
URL url = new URL(sURL); VgY6M_V  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); W<O/LHKHdn  
httpConnection.setRequestProperty("User-Agent","NetFox"); <Vh5`-J  
String sProperty = "bytes="+nStartPos+"-"; pvWj)4e  
httpConnection.setRequestProperty("RANGE",sProperty); t"~X6o|R  
Utility.log(sProperty); 1 K^-tms  
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InputStream input = httpConnection.getInputStream(); ZOppec1D  
//logResponseHead(httpConnection); eH*i_g'  
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byte[] b = new byte[1024]; cdI"=
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int nRead; c>r~pY~$  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) &P*r66  
{ >$3 =yw%  
nStartPos += fileAccessI.write(b,0,nRead); uVX,[%*P  
//if(nThreadID == 1) _S*QIb
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// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); *y+K{ fM1  
} ignOF  
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Utility.log("Thread " + nThreadID + " is over!"); 2]x,joB  
bDownOver = true; <h~uGBS"  
//nPos = fileAccessI.write (b,0,nRead);
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} !af;5F  
catch(Exception e){e.printStackTrace ();} {)kL7>u]^V  
} $fPiR  
} 3EA_-?  
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//打印回应的头信息 od!s5f!  
public void logResponseHead(HttpURLConnection con) QY\'Uu{  
{ `$JOFLa  
for(int i=1;;i++) W3X;c*j  
{ or)fx/%h  
String header=con.getHeaderFieldKey(i); |\C.il7  
if(header!=null) ,W]}mqV%.'  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); :4\_upRE  
Utility.log(header+" : "+con.getHeaderField(header)); h7xgLe@  
else h-m0Ro?6  
break; h,/3}  
} b$*G&d5  
} Jcp=<z*0  
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public void splitterStop() @}%kSn5y:  
{ Idj Z2)$  
bStop = true; D [v225  
} mndEB!b  
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} xKT;1(Mk  
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/* 1P BnGQYM  
**FileAccess.java F=UW[zy/[  
*//文件访问(定位，写) COH.`Tv{*  
package NetFox; #S|On[Q!  
import java.io.*; h`tf!MD]  
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public class FileAccessI implements Serializable{ '?$<k@mJW  
I wu^@  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 |g\CS4$  
RandomAccessFile oSavedFile; |c2;`T#`o  
long nPos; "nNT9 K|  
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public FileAccessI() throws IOException `K2vG`c  
{ fKs3H?|  
this("",0); CZCVC (/u  
} 2\Yv;J+;  
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/DSy/p0%  
public FileAccessI(String sName,long nPos) throws IOException RS7J~Q  
{ Vl:M6d1  
oSavedFile = new RandomAccessFile(sName,"rw"); A<[w'"  
this.nPos = nPos; <.@w%rvG  
oSavedFile.seek(nPos); Sh<A936/E  
} (B].ppBii  
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public synchronized int write(byte[] b,int nStart,int nLen) L\t!)X-4  
{ 4DGKZh'm"  
int n = -1; \JF 2'm\M  
try{ ><)fK5x  
oSavedFile.write(b,nStart,nLen); r+MqjdXG  
n = nLen; :O*62olC5  
} Tz/[P:O3  
catch(IOException e) 7{[i)  
{ .R@euIva
 
e.printStackTrace (); FJB /tg  
} ~HBx5Cpi  
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return n; &Qv%~dvW  
} sDy~<$l?  
cdfnM%`>\  
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} zOL*XZ0c  
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/* JaJyH%+$!  
**SiteInfoBean.java wV{VV?h}  
*/ Wp=&nh  
package NetFox; XP@&I[J3sI  
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public class SiteInfoBean { c=IjR3F  
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private String sSiteURL; //Site's URL 9
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private String sFilePath; //Saved File's Path v/G^yZa  
private String sFileName; //Saved File's Name ??Dv\yLZI  
private int nSplitter; //Count of Splited Downloading File *18J$  
EJTa~  
S%w67sGl4n  
public SiteInfoBean() h56s~(?O  
{//nSplitter的缺省值为5 G*^4CJ  
//default value of nSplitter is 5 ~#JX 0J=  
this("","","",5); |Fzt| \  
}
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) zm^5WH  
{ bY=Yb  
sSiteURL= sURL; z-h7v5i"  
sFilePath = sPath; yc@:*Z  
sFileName = sName; bKPjxN?!9  
this.nSplitter = nSpiltter; ?*U:=|
  
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`
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} ch0x*[N@  
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public String getSSiteURL() N_y#Y{c{(  
{ (7}Zh|@W  
return sSiteURL; 2H`;?#Uq:  
} vb k4  
:j% B(@b  
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public void setSSiteURL(String value) yI$MqR  
{ unkA%x{W;  
sSiteURL = value; X0%BE!  
} Z-z(SKL  
&d[%  
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public String getSFilePath() 3_c4+u"6  
{ [[8h*[:  
return sFilePath; ig:z[k?  
} \&%y4=y<sE  
v!rOT/I  
H?dEgubg7]  
public void setSFilePath(String value) ZvW&%*k=  
{ O9MBQNwjA  
sFilePath = value; z%WOv~8~  
} ]hA]o7k  
LfG$?<}hR  
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public String getSFileName() dY]iAJ  
{ K|{&SU_m  
return sFileName; q|R$A8)L.  
} 4S,/Z{ J.  
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public void setSFileName(String value) SrSm%Dv  
{ *
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sFileName = value; %Wb$qpa  
} / , .rUn1  
)]
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public int getNSplitter() ("j*!Dsd  
{ [fXC ;c1  
return nSplitter; #Xd#Ncj  
} &pLCN[a  
]7_O#MY1  
8*yky  
public void setNSplitter(int nCount) tsqWnz=)  
{ R{Qvpd$y  
nSplitter = nCount; ogKd}qTov  
}  ,zrShliU  
} KXga{]G:  
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jT
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/* Jl^THoEL  
**Utility.java JB\BP$ap  
*/ &5;y&dh  
package NetFox; ffE>%M*  

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=)y=39&;/  
public class Utility { aQhr$aH  
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public Utility() O\qY?)  
{ oq}Q2[.b  
vH9Gf  
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} wKs-<b%;  
Yo#F;s7  
//线程睡眠 0_5j(  
public static void sleep(int nSecond) 7u7 <"?v=  
{ )VCRbz"[g  
try{ H(Q|qckj  
Thread.sleep(nSecond); w*s#=]6
 
} zE<GwVI~  
catch(Exception e) 2wG4"  
{ /Q[M2DN@  
e.printStackTrace (); }]?U. ]-  
} C:d$
 
} #NLLlEE  
jo8;S?+<|?  
//日志 $C !Mk  
public static void log(String sMsg) Eq?d+s>  
{ dd%-bI^  
System.err.println(sMsg); p~THliwd  
} 6 bnuC  
&OSyU4r  
Nd4!:.  
public static void log(int sMsg) j;b<oQH  
{ 1z[GYRSt  
System.err.println(sMsg); y:+s*x6Vg  
} s%R'c_cGZ  
} -'!%\E;5  
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`L=$,7`  
/* S4Vv _k-&  
**TestMethod.java sZhl.[&zo  
*/ NTtRz(  
package NetFox; :+>:>$ao  
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public class TestMethod { :Gz#4k  
zl!`*{T{  
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public TestMethod() /M "E5  
{ ///xx/weblogic60b2_win.exe <KDl2>O  
try{ Rl"" aZ  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); yxa~Rz/  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); 3yAzt*dZ  
SiteFileFetch fileFetch = new SiteFileFetch(bean); vYNh0)$%F  
fileFetch.start(); J12ZdC'O  
} ?=uw0~O[  
catch(Exception e){e.printStackTrace ();} b]h]h1~hHH  
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4;ig5'U,  
} 5PQs1B  
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public static void main(String[] args) zoV-@<Eh  
{ jF\J+:5M  
new TestMethod(); I!;#Nk>  
} ,e ~@  
} [T.BK:  
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