http断点续传简单实现（java)

/* 0&|-wduR=  
**SiteFileFetch.java +Y+kx"8  
*/ "=)`*"rr  
package NetFox; >jm9x1+C  
import java.io.*; {1mD(+pJ{  
import java.net.*; n%}0hVu  
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public class SiteFileFetch extends Thread { {[eY/)6H  
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SiteInfoBean siteInfoBean = null; //文件信息Bean Yi3DoaS;"  
long[] nStartPos; //开始位置 kBkh
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long[] nEndPos; //结束位置 +=QboUN  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 u&:jQ:[  
long nFileLength; //文件长度 L!5HE])<)  
boolean bFirst = true; //是否第一次取文件 !!AutkEg>  
boolean bStop = false; //停止标志 (<t)5?@%  
File tmpFile; //文件下载的临时信息 f#?R!pR  
DataOutputStream output; //输出到文件的输出流 ^"I!+Teb  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） lnhZ!_  
public SiteFileFetch(SiteInfoBean bean) throws IOException \4DH&gZ[  
{ kK(,FB  
siteInfoBean = bean; e): &pqA  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); xK f+.6 wz  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); 8GX@76o  
if(tmpFile.exists ()) ;iWCV&>w  
{ W NCdk$  
bFirst = false; L=>N#QR7  
read_nPos(); *Co+UJjT  
}
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else `%VrT`  
{ 6mZFsB  
nStartPos = new long[bean.getNSplitter()]; .nnA
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nEndPos = new long[bean.getNSplitter()]; _nF_RpS  
} JL1Whf  
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} 2gi`^%#k]  
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public void run() hhpH)Bi=  
{ FRr<K^M  
//获得文件长度 +aMPwTF:3  
//分割文件 3j6$!89'  
//实例FileSplitterFetch z;LntQZp-  
//启动FileSplitterFetch线程 4IVCTz[  
//等待子线程返回 N9hBGa$  
try{ D n^RZLRhy  
if(bFirst) DLVf7/=3~  
{ q~lmOT~E  
nFileLength = getFileSize(); giv cq'L  
if(nFileLength == -1) 3;&N3:,X  
{ -LF^u;s8&S  
System.err.println("File Length is not known!"); $8b/"Qm  
} 8ARpjYZP  
else if(nFileLength == -2) -YYQnN  
{ z5?xmffB  
System.err.println("File is not access!"); U_+>4zdm  
} *
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else @f5X AK?  
{ o(}vR<tD\  
for(int i=0;i<nStartPos.length;i++) { Uh/ ~zu  
{ ;Q ]bV52  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); ]P-;]*&=  
} h[Hw9$31  
for(int i=0;i<nEndPos.length-1;i++) MD&Ebq5V  
{ 4:7z9h]
 
nEndPos = nStartPos[i+1]; Bb m1&d#  
} 1L3L!@  
nEndPos[nEndPos.length-1] = nFileLength; &
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} M!,WU
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}  {sbQf7)  
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//启动子线程 yPW?%7 h  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; 4Vh#Ye:`  
for(int i=0;i<nStartPos.length;i++) `CO?} rW  
{ 0^4Tem@  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), )
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siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), ~R3@GaL1  
nStartPos,nEndPos,i); !pgkUzMW  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos);
|iU#!+zY  
fileSplitterFetch.start(); `Q,03W#GJ%  
} a *>$6H;  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 'z@(,5  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); ?EdF&^[3rD  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", (c_E*>c)  
nEndPos = " + nFileLength); !fY'^Ya?  
// fileSplitterFetch[nPos.length-1].start(); >%t"VpvR  
gWRSS=8%  
>Qr(#Bt)  
//等待子线程结束 (Zp'|hx8o  
//int count = 0; Fq:BRgCE  
//是否结束while循环 S'q (Qo  
boolean breakWhile = false; 0I1bY]*  
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while(!bStop) oJEind>8O  
{ JS}iNS'X  
write_nPos(); D >$9(  
Utility.sleep(500); jCkYzQUPz  
breakWhile = true; aVEg%8  
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for(int i=0;i<nStartPos.length;i++) x^&D8&4^  
{ ; &$djP  
if(!fileSplitterFetch.bDownOver) rz5AIe>Hm  
{ Cjdw@v0;  
breakWhile = false; 7xqTT
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break; a%cCR=s=  
} =XuBan3B>  
} !;>j(xc  
if(breakWhile) Y<odXFIS  
break; M, f6UYo=  
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//count++; 0@k)Cz[0;  
//if(count>4) :@mb.'%*!  
// siteStop(); cyL"?vR*<  
} R^4JM,v9x`  
}Ndknut,  
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System.err.println("文件下载结束！"); Tc$Jvy-G4A  
} @p~f*b4H?  
catch(Exception e){e.printStackTrace ();} R1)v;^B|)  
} :+06M@  
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//获得文件长度 'GcN9D  
public long getFileSize() 6B'd]Fe  
{  [,JUC<  
int nFileLength = -1; yy8h8{=g  
try{ ei%L[>N  
URL url = new URL(siteInfoBean.getSSiteURL()); Pv@Lx+k  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 1ayL*
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httpConnection.setRequestProperty("User-Agent","NetFox"); 3@7IY4>o  
#l2KJ7AMK  
9\y\{DHd  
int responseCode=httpConnection.getResponseCode(); |1!RvW:[!  
if(responseCode>=400) F|nJ3:v  
{ <2{g[le  
processErrorCode(responseCode); ROb2g|YXG  
return -2; //-2 represent access is error hhRUC&Y%V  
} a*/%EP3  
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;d5d$Np@m&  
String sHeader; ufq9+}  
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for(int i=1;;i++) X!6oviT|m  
{ ,%Sf,h?"^  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); 20h+^R3{Z  
//Utility.log(in.readLine()); II;   
sHeader=httpConnection.getHeaderFieldKey(i); <l>o6K  
if(sHeader!=null) ?9W2wqN>o  
{ J7a_a>Y  
if(sHeader.equals("Content-Length")) rW),xfo0  
{ oQ YmywY  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); 4}&$s  
break; D6z*J?3^#&  
} $1KvL8
  
} cug=k  
else .A%*AlX  
break; M4rI]^lJ  
} 5=@q!8a*  
} K%i9S;~  
catch(IOException e){e.printStackTrace ();} `YL)[t? V  
catch(Exception e){e.printStackTrace ();} !I)wI~XF)5  
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Utility.log(nFileLength); d x52[W  
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return nFileLength; Lfr>y_i;F  
} Ynxzkm S  
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//保存下载信息（文件指针位置） }LYK:?_/  
private void write_nPos() %0&c0vT  
{ u/6b.hDO  
try{ ^V
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output = new DataOutputStream(new FileOutputStream(tmpFile)); ?xX9o  
output.writeInt(nStartPos.length); 0Tp,b (;n  
for(int i=0;i<nStartPos.length;i++) C]dK/~Z#r  
{ A4Sb(X|j  
// output.writeLong(nPos); ~3'}^V\  
output.writeLong(fileSplitterFetch.nStartPos); .^hk^r  
output.writeLong(fileSplitterFetch.nEndPos); "1I\~]]  
} @vHj>N  
output.close(); ,2>nr goM  
} 1[4 2f#  
catch(IOException e){e.printStackTrace ();} e]5 n4"]D)  
catch(Exception e){e.printStackTrace ();} E=3UaYr  
} S:F8`Gh  
{)K
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//读取保存的下载信息（文件指针位置） ~Y)h[  
private void read_nPos() RvXK?mL4F  
{ :n0czO6E  
try{ ?j:U<TY)  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); <&47W  
int nCount = input.readInt(); <0sT  
nStartPos = new long[nCount]; GI.=\s  
nEndPos = new long[nCount]; Lnk(l2~U  
for(int i=0;i<nStartPos.length;i++) 3{/[gX9  
{ ))NiX^)8^  
nStartPos = input.readLong(); SJ0IEPk  
nEndPos = input.readLong(); G_1`NyI  
} hf('4^  
input.close(); |i
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} DuvI2ZWP]  
catch(IOException e){e.printStackTrace ();} (?W[#.=7  
catch(Exception e){e.printStackTrace ();} q\uzmOh  
} #t8{z~t3  
:*g3PhNE  
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private void processErrorCode(int nErrorCode) ?yNg5z  
{ pVN) k  
System.err.println("Error Code : " + nErrorCode); (U?*Z/  
} Bk44 wz2X  
(^lw<$N  
N.1@!\z@@  
//停止文件下载 ps@;Z?Q  
public void siteStop() 1&2
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{ :i};]pR  
bStop = true; I 7 B$X=  
for(int i=0;i<nStartPos.length;i++) XLq%nVBM8\  
fileSplitterFetch.splitterStop(); Gm1[PAj  
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} rY:A
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} Et0[HotO  
//负责部分文件的抓取 4z*An}ol]  
**FileSplitterFetch.java \ )'`F; P  
*/ #]vs*Sz  
package NetFox; Ex`!C]sQ  
3v?R"2\qS  
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import java.io.*;  Oye:V  
import java.net.*; TQ`4dVaf  

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public class FileSplitterFetch extends Thread { K3I|d;Y~X!  
K
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String sURL; //File URL }]BH
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long nStartPos; //File Snippet Start Position +r<d z  
long nEndPos; //File Snippet End Position I}hY @  
int nThreadID; //Thread's ID V;-$k@$b.  
boolean bDownOver = false; //Downing is over 2leTEs5aK`  
boolean bStop = false; //Stop identical kKlcK_b;  
FileAccessI fileAccessI = null; //File Access interface *= ;M',nx  

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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException r0'6\MS13  
{ HQ0fY  
this.sURL = sURL; 2Y-NxW^]  
this.nStartPos = nStart; }j\_XaB  
this.nEndPos = nEnd; y} W-OLE  
nThreadID = id; j
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fileAccessI = new FileAccessI(sName,nStartPos);//定位 sc)}r_|g  
} GB&^<@  

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public void run() +[_mSt  
{ PgMU|O7To  
while(nStartPos < nEndPos && !bStop)
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{ xa&5o`>1G  
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try{ I/vQP+w O  
URL url = new URL(sURL); ze_q+Z  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 8G<{L0J%!  
httpConnection.setRequestProperty("User-Agent","NetFox"); r&0IhE  
String sProperty = "bytes="+nStartPos+"-"; >u=Dc.lX  
httpConnection.setRequestProperty("RANGE",sProperty); ?y`we6~\1  
Utility.log(sProperty); S?BI)shmg  
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*rH#k?  
InputStream input = httpConnection.getInputStream(); QHmF,P  
//logResponseHead(httpConnection); )&pcRFl  
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byte[] b = new byte[1024]; q37d:Hp  
int nRead; "'@>cJ=  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) +B#+'  
{ o-7,P RmKN  
nStartPos += fileAccessI.write(b,0,nRead); \YMe&[C:o  
//if(nThreadID == 1) _GF{Duxh  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); i[V\RKH*F  
} hwj:$mR  
[PP&}.k4"  
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Utility.log("Thread " + nThreadID + " is over!"); NG\g_^.M
 
bDownOver = true; {I^@BW-  
//nPos = fileAccessI.write (b,0,nRead); ,B8u?{O  
} s+a} _a:  
catch(Exception e){e.printStackTrace ();} }Y
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} ?j^:jV  
} [==x4Nb  
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//打印回应的头信息 .tQeOZW'  
public void logResponseHead(HttpURLConnection con) T@P[jtH<d  
{ k,GAHM"'  
for(int i=1;;i++) Q*K31Ln  
{ !U[/P6 +0  
String header=con.getHeaderFieldKey(i); nd3n'b  
if(header!=null) ,SB5"  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); =,w(D~ps  
Utility.log(header+" : "+con.getHeaderField(header)); bZf}m=C!  
else W^"C|4G}  
break; 1wTPT,k  
} AdGDs+at,  
} e,8[fp-7  
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public void splitterStop() .d;|iwl  
{ }P*x/z~  
bStop = true; kC8M2|L  
} tcD DX'S  
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} J2avt  
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/* u [Dz~  
**FileAccess.java >HL$=J_K?  
*//文件访问(定位，写) @CNe)&U  
package NetFox; 8m"(T-wb6{  
import java.io.*; 1a@b-V2 d&  
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<;P40jDL  
public class FileAccessI implements Serializable{ S!6 ? b5  
9?38/2kX4  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 &qMt07  
RandomAccessFile oSavedFile; :N#8|;J1Fl  
long nPos; ["N_t:9I  
k
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3;Y9<  
public FileAccessI() throws IOException @|6#]&v`  
{ $az9Fmta  
this("",0); .9VhDrCK  
} dBb &sA-A  
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public FileAccessI(String sName,long nPos) throws IOException 5[0W+W  
{ ,?oC+9w  
oSavedFile = new RandomAccessFile(sName,"rw"); ./i5VBP5  
this.nPos = nPos; `NB6Of*/  
oSavedFile.seek(nPos); w0&|8y  
} YMr2Dv\y  
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public synchronized int write(byte[] b,int nStart,int nLen) a?1lj,"~R  
{ )uRR!<"~  
int n = -1; f~P~%  
try{ 34c+70x7  
oSavedFile.write(b,nStart,nLen); . ytxe!O  
n = nLen; S(#v<C,hd  
} ]Il}ymkIZ  
catch(IOException e) 8/"R&yAh  
{ WbJ  
e.printStackTrace (); JJ4w]Dd4  
} .Ge`)_e  
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return n; /K :H2?J  
} >41K>=K  
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} =<[M$"S7d6  
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/* Oh;V%G  
**SiteInfoBean.java TR'<D9kn  
*/ 5gKXe4}\/|  
package NetFox; =z*SzG  
 N~vK8j@  
OICH:(t_  
public class SiteInfoBean { uFnq3m^u  
Y$0K}`{  
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private String sSiteURL; //Site's URL "?S>}G\  
private String sFilePath; //Saved File's Path Rc(E';uc  
private String sFileName; //Saved File's Name 7;@o]9W  
private int nSplitter; //Count of Splited Downloading File <tgfbY^nL  
nj=nSD  
v
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public SiteInfoBean() XM~eocn  
{//nSplitter的缺省值为5 iLk"lcX  
//default value of nSplitter is 5 r1a/'+  
this("","","",5); S N;1F  
} vl>_;}W7  
ks7id[~&iY  

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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter)
[B@R(z=H  
{ L*zfZ&  
sSiteURL= sURL; 8d[!"lL  
sFilePath = sPath; C
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sFileName = sName; S9{&.[O  
this.nSplitter = nSpiltter; 2[I[I*"_d  
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}  
} i?n#ge  
<(_${zR  
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public String getSSiteURL() QRHM#v S  
{ cF}9ldc  
return sSiteURL; HY,VJxR[  
} sWFw[Y>  
@<z#a9  
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public void setSSiteURL(String value) I>:.fHvUC  
{ ,~>u<Wc!S  
sSiteURL = value;
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} ofuQ`g1hb  
UQO?hZ!y/.  
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public String getSFilePath() 6.6x$y3v  
{ yX1OJg[s,  
return sFilePath; <4Ik]Uz^  
} u"-."_  
,B$e'KQ  
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public void setSFilePath(String value) pykRi#[UrX  
{ nmoC(| r  
sFilePath = value; t'*2)U  
} /_i]bM7W  
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public String getSFileName() $j&2bO5M  
{ Oee>d
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return sFileName; #Ti5G"C  
} eb7~\|9l1i  
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public void setSFileName(String value) 'J:xTp  
{ ?<~P)aVVj  
sFileName = value; wj9Hh  
} `g'z6~c7n  
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public int getNSplitter() S<>u  
{ s=1w6ZLD  
return nSplitter; Atod&qH  
} k!{h]D0  
~"22X`;h[G  
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public void setNSplitter(int nCount) vnH[D)`@  
{ Vm%0436wOY  
nSplitter = nCount; a]=j  
} 85#+_}#  
} ?}<Wmy2A  
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j,v2(e5:  
/* j]  
**Utility.java U}SN#[*  
*/  &W? hCr  
package NetFox; J" U!j  
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public class Utility { uY:u[  
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public Utility() gF&HJF 0x  
{ ju(QSZ|;  
`:5W1D(  
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} <%=@Ue  
zN>tSdNkI-  
//线程睡眠 H)NT2@%{P  
public static void sleep(int nSecond) T@j@IEGH  
{
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try{ Jl{g"N{2u'  
Thread.sleep(nSecond); e'&<DE)  
}
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catch(Exception e) RaAvPIJa |  
{ 8~vE  
e.printStackTrace (); d5 U+]g  
} ?o_D#gG*  
} ,{s
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/  
*+>Q
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//日志 ePe/@g1K*  
public static void log(String sMsg) "U iv[8B  
{ \-RVPa8k  
System.err.println(sMsg); kcZz WG|n  
} 5 DvD  
}+BbwBm&  
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public static void log(int sMsg) P*{*^DN  
{ kT4Oal+4  
System.err.println(sMsg); -+&sPrQ  
} Xv?'*2J  
} |Whkq/Zg  
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!z?;L_Lb  
/* ~19&s
~  
**TestMethod.java 9X
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*/ ?V(h@T  
package NetFox; $s!2D"wl n  
>l(|c9OWM  
8aa`0X/6  
public class TestMethod { Dt]*M_  
2[Vs@X  
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public TestMethod() btv.M  
{ ///xx/weblogic60b2_win.exe v>p}f"$`  
try{ 17@#"uT0  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); mE3M$2}  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); ec"+Il  
SiteFileFetch fileFetch = new SiteFileFetch(bean); p|VgtQ/)%  
fileFetch.start(); d(;Qe}ok>  
} DT>Gi
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catch(Exception e){e.printStackTrace ();} aDVBi: _  
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\,yX3R3}.~  
} kac]Rh8vO  
4 X6_p(  
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public static void main(String[] args) 4%,E;fB?=  
{ bs\7 juHt  
new TestMethod(); OjBg$f~0F  
} E~'Q
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} Afo qCF  
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